Battery coating for rechargable hearing systems

ABSTRACT

Embodiments of the invention include a method of preventing ferrite migration in a hearing aid including an antenna stack and a battery stack wherein the antenna stack sits on the battery stack, the method comprising the steps of: conformally coating the top and sides of the antenna stack using a conformal coating material; and separately coating all the surfaces of the battery stack using a separate material.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional ApplicationsNos. 62/273,002, filed Dec. 30, 2015 (Attorney Docket No.33999-741.101), and 62/433,195, filed Dec. 12, 2016 (Attorney Docket No.33999-741.102), which applications are incorporated herein by reference.

The subject matter of this application is related to the subject matterof U.S. patent applications Ser. Nos. ______, filed Dec. 19, 2016(Attorney Docket No. 33999-741.201), Ser. No. ______, filed Dec. 19,2016 (Attorney Docket No. 33999-747.201), and Ser. No. ______, filedDec. 19, 2016 (Attorney Docket No. 33999-748.201) and PCT ApplicationsSerial Nos. PCT/US2016/______, filed Dec. 19, 2016 (Attorney Docket No.33999-741.601) and PCT/US2016/______, filed Dec. 19, 2016 (AttorneyDocket No. 33999-747.601), which applications are incorporated herein byreference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention is directed to apparatus and methods forpreventing fluid ingress in a rechargeable battery and, moreparticularly to methods and coatings for preventing the ingress offluids and resulting electrical shorts in rechargeable batteries for usein hearing aids.

Description of Background Art

Contact Hearing Systems, such as those described herein, generallyinclude a contact hearing device, an ear tip and an audio processor.Contact hearing systems may also include additional components, such asan external communication device. An example of such system is a lightdriven hearing-aid system that transmits audio signal by laser totympanic membrane transducer (TMT) which is placed on an ear drum.

Contact hearing devices for use in contact hearing systems may comprisea tiny actuator connected to a customized ring-shaped support platformthat floats on tissue in the ear canal on or around the eardrum, andresides in the ear much like a contact lens resides on the surface ofthe eye. In such contact hearing devices, the actuator directly vibratesthe eardrum, causing energy to be transmitted through the middle andinner ears to stimulate the brain and produce the perception of sound.In some contact hearing systems, the contact hearing device may comprisea photodetector, a microactuator connected to the photodetector and asupport structure supporting the photodetector and microactuator.

Contact hearing systems may further include an Audio Processor (whichmay also be referred to as a BTE). The audio processor serves as asystem for receiving and processing audio signals. Such audio processorsmay include one or more microphones adapted to receive sound whichreaches the user's ear along with one or more components for processingthe received sound and digital signal processing electronics andsoftware which are adapted to process the received sound, includingamplification of the received sound.

Contact hearing systems may also include ear tips which are adapted tofit into the ear of a user and transmit sound to the contact hearingdevice positioned at the distal end of the user's ear canal. Ear tipsare designed to be placed into and reside in the ear canal of a user,where the structure is adapted to receive signals intended to betransmitted to the user's tympanic membrane or to a device positioned onor near the user's tympanic membrane (such as, for example, a contacthearing device). In light driven hearing aids the signals may betransmitted by light, using, for example, a laser positioned in the eartip. In such light driven contact hearing systems, the ear tip may bereferred to as a light tip.

Because of the environment in which many hearing aids operate theBTE/processor and internal electronics are exposed to various forms ofmoisture. Ingress of that moisture into the BTE/processor may result indeleterious effects. The deleterious effects of moisture ingress areparticularly significant when the moisture impacts the battery. Moisturewhich comes in contact with a battery, including the electronics andrecharging circuitry around the battery has deleterious impact on thefunction of the battery, including shorting and/or the creation ofcorrosion, particularly in the presence of electric fields, such asthose generated when the battery is being charged. It would, therefore,be advantageous to develop methods and coatings to ensure that batteriesand their associated components are fully protected from moistureingress.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of embodimentsof the present inventive concepts will be apparent from the moreparticular description of preferred embodiments, as illustrated in theaccompanying drawings in which like reference characters refer to thesame or like elements. The drawings are not necessarily to scale,emphasis instead being placed upon illustrating the principles of thepreferred embodiments.

FIG. 1 is a schematic illustration of a hearing aid system including acontact hearing device according to the present invention.

FIG. 2 is a block diagram of a hearing aid system according to thepresent invention.

FIG. 3 is a top view of a tympanic lens according to the presentinvention.

FIG. 4 is a bottom view of a tympanic lens according to the presentinvention.

FIG. 4A is a side view of a tympanic lens according to the presentinvention.

FIG. 5 is an exploded top view of a tympanic lens according to thepresent invention.

FIG. 6 is a side view of a distal end of a microactuator and umboplatform according to the present invention.

FIG. 7 is a side view of a tympanic lens according to the presentinvention positioned on the tympanic membrane of a user.

FIG. 7A is a further side view of a tympanic lens according to thepresent invention with the tympanic lens positioned on the tympanicmembrane of a user.

FIG. 7B is a view of a proximal end of a tympanic lens including amicroactuator and bias springs according to the present invention.

FIG. 7C is an alternate view of a proximal end of a tympanic lensincluding a microactuator and bias springs according to the presentinvention.

FIG. 7D, 7E, and 7F are circuit diagrams of the tympanic lens, includinga photodetector and microactuator.

FIG. 8 is an illustration of a behind the ear device connected to alight tip in accordance with the present invention.

FIG. 9 is an illustration of a light tip and cable according to thepresent invention.

FIG. 10 is an exploded view of a light tip and cable assembly accordingto the present invention.

FIG. 10A is an exploded perspective view of an emitter according to thepresent invention.

FIG. 11 is a perspective view of a light tip storage unit and chargeraccording to the present invention.

FIG. 12 is an exploded view of a light tip storage unit and chargeraccording to the present invention.

FIG. 13 is a side perspective view of a behind the ear device accordingto the present invention.

FIG. 14 is a side perspective view of a behind the ear device with anaccess cover removed according to the present invention.

FIG. 15 is a perspective view of a behind the ear device according tothe present invention with the access cover and BTE housing removed.

FIG. 15A is an exploded view of a portion of a behind the ear device,including the battery and charging coil according to the presentinvention.

FIG. 15B is an illustration of the battery and coil antenna with backiron, including the coatings used to protect the battery and coilstructure.

FIG. 16 is an illustration of an alignment tool mounted on a mold of anear canal according to the present invention.

FIG. 17 is an illustration of a verification fixture according to thepresent invention.

FIG. 18 is a block diagram of the circuitry in a behind the ear deviceaccording to the present invention.

FIG. 19 is a flow diagram of the state machine for the behind the eardevice according to the present invention.

FIG. 20 is a flow diagram of the state machine for a charger accordingto the present invention.

FIG. 21 is a flow diagram of the state machine for the BTE according tothe present invention.

FIG. 21A is a flow diagram of the state machine for a charger accordingto the present invention.

FIG. 22 is an illustration of a packet structure for data transmissionbetween the behind the ear device and charger according to the presentinvention.

FIG. 23 is a state diagram of the BTE charging process.

FIG. 24 is an illustration of a cable sizing tool according to thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic illustration of a hearing aid system 10, includinga contact hearing device 20 according to the present invention. In FIG.1, audio processor 30 is connected to light tip 120 by cable 260, whichincludes taper tube 250. Light tip 120 is adapted to radiate lightpulses 40 to tympanic lens 100 which is positioned on a user's tympanicmembrane TM in a manner which allows it to drive the user's umbo UMdirectly.

FIG. 2 is a block diagram of a hearing aid system 10 according to thepresent invention. In FIG. 2, sound 340 is detected by microphone 310,which is connected to analog to digital converter 320. Sound signalsprocessed by analog to digital converter 320 are transmitted to digitalsignal processor 330. Digital signal processor 330 is, in turn,connected to emitter 290, which radiates light 40 to photodetector 130.The output of photodetector 130 drives microactuator 140, which includesumbo lens 220. Umbo lens 220 is positioned on a user's tympanic membraneTM in a manner which allows it to move the user's tympanic membranedirectly.

FIG. 3 is a top view of a tympanic lens 100 according to the presentinvention. FIG. 4 is a bottom view of a tympanic lens 100 according tothe present invention. FIG. 4A is a side view of a tympanic lens 100according to the present invention. FIG. 5 is an exploded top view of atympanic lens 100 according to the present invention. In the tympaniclens of FIGS. 3, 4, 4A, and 5 a perimeter platform 155 is mounted on achassis 170. Perimeter platform 155 may include a sulcus platform 155 ata medial end of perimeter platform 155. Chassis 170 may further includebias springs 180 (which may also be referred to as torsion springs)mounted thereon and supporting microactuator 140. Microactuator 140 isconnected to drive post 200, which is connected to umbo lens 240 byadhesive 210. Chassis 170 further supports grasping tab 190 andphotodetector 130.

FIG. 6 is a side view of a distal end of a microactuator 140 and umboplatform 160 according to the present invention. Microactuator 140includes membrane 240 and reed tip 230, which is positioned at thedistal end of microactuator reed 350 (not shown in this view). Umboplatform 16, which is attached to microactuator 140 includes drive post200, adhesive 210 and umbo lens 230. Umbo platform 160 is attached tomicroactuator reed 350 at a proximal end of drive post 200.

FIG. 7 is a side view of a tympanic lens 100 according to the presentinvention where tympanic lens 100 is positioned on the tympanic membraneTM of a user. FIG. 7A is a further side view of a tympanic lens 100according to the present invention positioned on the tympanic membraneTM of a user. In FIGS. 7 and 7A, tympanic lens 100 comprises perimeterplatform 155 which includes sulcus platform 150 at a distal end thereof.Perimeter platform 155 is connected to chassis 170, which supportsmicroactuator 140 through bias springs 180. Microactuator 140 includesmicroactuator reed 350 extending from a distal end thereof.Microactuator reed 350 is connected to umbo lens 220. Chassis 170further supports photodetector 130, which is electrically connected tomicroactuator 140. In FIG. 7, perimeter platform 155 is positioned onskin SK covering the boney portion BN of the ear canal EC. The sulcusplatform portion of perimeter platform 155 is positioned at the medialend of the ear canal in the tympanic annulus TA. Umbo lens 200 ispositioned on umbo UM of tympanic membrane UM. In FIG. 7A, an oil layer225, of, for example, mineral oil is positioned between perimeterplatform 155 and skin SK and between umbo lens 220 and umbo UM.

FIG. 7B is a view of a proximal end of tympanic lens 100 includingmicroactuator 140 and bias springs 180 according to the presentinvention. FIG. 7C is an alternate view of a proximal end of tympaniclens 100 including bias springs 180 according to the present invention.The distal end of tympanic lens 100 includes bias springs 180 which areconnected to microactuator 140 and chassis 170 by hypotubes 182. Inembodiments of the invention, bias springs 180 include damper 185.Tympanic lens 100 may further include photodetector 130, which iselectrically connected to microactuator 140 by photodetector wires 186,photodetector PCB 188, microactuator wires 184 and microactuator PCB192. Microactuator PCB 192 may be protected by a potting material 194.Tympanic lens 100 further includes grasping tab 190. Microactuator 140further includes drive post 200 and membrane 240.

FIG. 7D, 7E, and 7F are circuit diagrams of tympanic lens 100, includingphotodetector 130 and microactuator 140. In FIGS. 7D and 7E, theelectrical output of photodetector 130 drives microactuator 140directly.

FIG. 8 is an illustration of a behind the ear device connected to alight tip in accordance with the present invention. In FIG. 8, BTE 110includes microphone 310 and light tip connector 270. BTE 110 isconnected to light tip 120 by cable 260. Light tip 120 includes tapertube 250 and emitter 290.

FIG. 9 is an illustration of a light tip and cable according to thepresent invention. In FIG. 9, cable 260 includes light tip connector 270at a proximal end of cable 260.

FIG. 10 is an exploded view of a light tip and cable assembly accordingto the present invention. In FIG. 10, lid 380 is illustrated.

FIG. 10A is an exploded perspective view of emitter 290 according to thepresent invention. In FIG. 10A, emitter 290 comprises diffuser 292,epoxy ring 294, cap 296, VCSEL 302, VCSEL wire 298, header 304, andcable 260. In embodiments of the invention, VCSEL 302 may be avertical-cavity surface-emitting laser.

FIG. 11 illustrates a light tip storage unit 360 with an integratedbattery charger according to the present invention. FIG. 12 is anexploded view of light tip storage unit 360 according to the presentinvention. In FIG. 12 light tip storage unit 360 comprises screws 450,PCB Assembly 470, center chassis assembly 460, release button 440,spring 430, wireless charging coil 410, magnet 420, upper housing 400,hinge pin 390, and lid 380.

FIG. 13 is a side perspective view of behind the ear device 110according to the present invention. FIG. 14 is a side perspective viewof behind the ear device 110 according to the present invention withaccess cover 370 removed. In FIG. 14, behind the ear device 110 includesaccess cover 370, microphone through holes 520, microphone ports 530,antenna 610, first switch SW1 550, programing socket 510, second switchSW2 560, and rocker switch 540. In embodiments of the invention, rockerswitch 540 may be used to control, for example, volume, programselection and/or to turn behind the ear 110 on and off.

FIG. 15 is a view of behind the ear device 110 according to the presentinvention with access cover 370 and BTE housing 375 removed. In FIG. 15,BTE 110 includes microphone through holes 520, antenna 610, switch SW1550, switch SW2 560, BTE chassis 580, battery 500, battery tab 590, PCMcircuit 570, main PCB 600, and microsquid connector 620. In embodimentsof the invention, PCM circuit 570 acts as an electronic protector forbattery 500.

FIG. 15A is an exploded view of a portion of behind the ear device 110,including battery 500 and coil antenna 630 (which may also be referredto as a charging coil) according to the present invention. In FIG. 15Abattery 500 is separated from coil antenna 630 by back iron 640 andspacer 650.

FIG. 15B is an illustration of battery 500 and coil antenna 630 withback iron 640 and spacer 650 including the coatings used to protectbattery 500 and coil antenna 630. In FIG. 15B, coil antenna 630, backiron 640 and spacer 650 form antenna stack 655. Antenna stack 655 iscovered by a first conformal coating 660, which protects antenna stack655 from fluid ingress. Battery 500 is coated with a second coatingmaterial 670, which may be, for example, Parylene. The interface betweenbattery 500 and antenna stack 655 does not include conformal coating660. Second coating material 670 coats all of battery 500, battery tab590, and PCM Circuit 570, including the interface between battery 500and antenna stack 655.

FIG. 16 is an illustration of an alignment tool 700 mounted on tympaniclens mold 710 according to the present invention. In FIG. 16, alignmenttool 700 includes chassis alignment feature 750 and photodetectoralignment feature 720. Chassis alignment feature 750 is used to alignchassis 170 of tympanic lens 100 (not shown) in tympanic lens mold 710.Photo Detector Alignment Feature 720 is used to align a photodetector130 (not shown), prior to gluing photodetector 130 in place on chassis170. In embodiments of the invention, photodetector alignment feature720 and chassis alignment feature 750 are custom designed for eachpatient using a digital model of the patient's anatomy.

FIG. 17 is an illustration of a verification fixture according to oneembodiment of the present invention. In FIG. 17, verification fixture760 includes ear canal mold 740 and tympanic lens mold 710. Ear canalmold 740 and tympanic lens mold 710 incorporate the anatomical detailsof the user for whom the tympanic lens 100 and light tip 120 are beingmanufactured. In embodiments of the invention, Ear canal mold 740 andtympanic lens mold 710 may be 3D printed. In embodiments of theinvention, in order to verify that emitter 290 and photodetector 130will be properly aligned when placed in the user's ear canal, light tip120 and tympanic lens 100 are placed into verification fixture 760 atthe locations and in the orientations they would have in the user's earcanal. Proper alignment may then be measured by exciting light outputfrom emitter 290 and measuring the electrical output from photodetector130.

FIG. 18 is a block diagram of the circuitry in a behind the ear deviceaccording to one embodiment of the present invention. In FIG. 18,programing socket 510 is connected to BLE circuitry 840, fuel gage 780and digital signal processor 790. BLE circuitry 840 is further connectedto digital signal processor 790. Push button circuitry 540, chargercircuitry 850, laser driver circuitry 800, laser voltage settingcircuitry 810, laser voltage measurement circuitry 820, and laserovercurrent protection circuitry are also connected to digital signalprocessor 790.

FIG. 19 is a flow diagram of the state machine for the behind the eardevice according to the present invention. In step 900 the system ispowered up. In step 902, the event counter is initialized. In step 904,the event life limit is read from device memory. In step 906, the eventthreshold is set to N, which is obtained from memory. In step 908, thestate machine is waiting for an event trigger. In step 910, the eventcounter is incremented when an event trigger is detected in step 908. Instep 912, the state machine is sent back to step 908 to wait for thenext event trigger unless the event counter is equal to N. If the eventcounter is equal to N in step 912, then an issue notification or alertis sent in step 914. In step 916, the user clears the notifications oralerts sent in step 914. In step 918, the device is repaired orserviced. In step 920, a technician clears the alerts after the unit hasbeen repaired or serviced.

FIG. 20 is a flow diagram of the state machine for a charger 360according to the present invention. In step 922, the charger is idleuntil a behind the ear device 110 is dropped into a slot in the charger.In step 924, the charger goes through a hysteresis period until a timertimes out. In step 926, the charger generates a random number sequence.In step 928, the charger sends the behind the ear device 110 asynchronization pattern. In step 930, the charger sends the behind theear device 110 an 8-bit unique ID. In step 932, the charger goes into ascanning mode. In step 934, the behind the ear device 110 goes into anadvertising mode. In step 936, the charger detects the behind the eardevice 110 and the charger and behind the ear device 110 are associated.In step 938, the charger profile is synchronized. In step 940, thecharger displays the charging status to a user. In step 942 the behindthe ear device 110 is removed from the slot by the user. In step 944,the charger disconnects from the behind the ear device 110 and goes backto step 922. In embodiments of the invention, the state diagram for acharger may be implemented without using steps 924, 932, 934, or 938.

In embodiments of the invention, step 938 may include providing aconnection to a remote storage device such as a cell phone or the cloud.Data may be transmitted to the remote storage device to, for example,upload data logs or, conversely, data may be downloaded to the hearingaid to, for example, update the firmware on the BTE.

FIG. 21 is a flow diagram of the state machine for a behind the eardevice 110 according to the present invention. In step 946, behind theear device 110 is idle until the presence of a charger 360 is detectedin step 948. In step 950, charger 360 and behind the ear device 110 aresynchronized. In step 952, behind the ear device 110 decodes an 8 bitunique ID transmitted by charger 360. In step 954, behind the ear device110 uses the unique ID to advertise its presence to charger 360 in a lowpower setting. In step 956, behind the ear device 110 establishesconnection with charger 360. In step 958, behind the ear device 110sends out fuel gage data to charger 360 every ten seconds. In step 960,behind the ear device 110 is removed from charger 360 by the user andthe counter data days are reset. Behind the ear device 110 is thenreturned to its idle state in step 946.

FIG. 21A is a flow diagram of the state machine for a charger accordingto the present invention. In step 980, the charger is idle until a BTE110 is dropped into a slot in the charger. In step 980, the chargerdetects the presence of the BTE. In step 982, the charger initiatescommunication with the BTE. In step 984, the charger authenticates theBTE to ensure that it is a BTE which is designed to be used with thecharger. If the BTE is not designed to be used with the charger, thenthe charger goes back to the idle state (step 978). If the chargerauthenticates the BTE in the slot, then, in step 986, the BTE transmitsits battery profile (state of charge, voltage, temperature, etc. to thecharger. In step 988, having authenticated the BTE and established itsbattery profile, the charger begins charging the battery. In step 990,the charger displays the status of the charger (e.g., the degree ofcharge) using, for example, diodes on the charger. In step 992, thecharger communicates with the BTE to update its battery profile. Step992 may be repeated at predetermined intervals (e.g., every 10 Minutes).In step 994, the charger determines whether the batter is fully charged(e.g., has reached a voltage of 4.18 Volts). In step 996, the chargerhas determined that the battery is fully charged and it goes into atopping off cycle, wherein the charger comes on at reduced duty cyclesfor predetermined periods of time, with each subsequent period of timeusing a reduced duty cycle. After the topping off cycle the chargerstops charging the battery in step 998. In step 1000, the charger checksthe battery status at predetermined intervals (e.g., every hour) todetermine whether the charge level has dropped below a predeterminedlevel (e.g., 4.15 Volts). If the charge level has dropped below thepredetermined level, then the charger goes back to step 992 and restartsthe charging process.

FIG. 22 is an illustration of packet structure 962 for data transmissionbetween the behind the ear device and charger according to the presentinvention. In FIG. 22, packet structure 962 comprises preamble 964,8-bit unique id 966 and EOF 968.

FIG. 23 is a state diagram of the BTE charging process.

FIG. 24 is an illustration of cable sizing tool 970 according to thepresent invention. In one embodiment of the invention, cable sizing tool970 includes dummy BTE 972, sizing cable 974 and sizing markings 976. Inembodiments of the invention, dummy BTE 972 may be sized and shaped tohave the same dimensions as the behind the ear device being sold to theuser in order to ensure that the sizing cable accurately reflects thesize of the final cable. In practice, the health care provider positionsdummy BTE 972 behind the ear of a user and then uses sizing markings 976to identify the correct length cable for that user.

The present invention is directed to a hearing aid system 10 including acontact hearing device (which may also be referred to as a CHD) 20 and acharger 360 (which may also be referred to as a light tip storagedevice). Hearing aid system 10 may further include signal processingsoftware for processing signals received by CHD 20.

In embodiments of the invention, hearing aid system 10 may comprise anaudio processor 30 and a tympanic lens (which may also be referred to asa tympanic membrane transducer) 100. Tympanic lens 100 may be placeddeep in the ear canal EC and adjacent to the tympanic membrane TMthrough a non-invasive and non-surgical procedure. Tympanic lens 100makes contact with the umbo of the tympanic membrane TM and is intendedto remain in the ear for extended periods.

In embodiments of the invention, audio processor 30 may comprise abehind the ear unit (which may also be referred to as a BTE) 110 and anattached light tip 120.

In embodiments of the invention, BTE 110 may comprise one or moremicrophones 310, digital signal processing circuitry (not shown) and arechargeable battery 500. BTE 110 may be used to receive and processaudio signals which processed signals are then transmitted to tympaniclens 100 through light tip 120.

Tympanic lens 100 is placed deep in the ear canal and adjacent to thetympanic membrane TM through a non-invasive and non-surgical procedure.Tympanic lens 100 makes contact with the umbo UM of the tympanicmembrane TM and is intended to remain in the ear until removed by aphysician. As used herein, the Umbo refers to the depressed area on theouter surface of the tympanic membrane. In one embodiment, the presentinvention involves the placement of a tympanic lens on the tympanicmembrane to provide mechanical vibrations to the tympanic membrane. Bydriving the tympanic membrane directly, the present invention is able toprovide hearing assistance which exceeds the range of typical airconduction hearing aids, thus allowing users to hear more clearly athigh frequencies (e.g., frequencies in the 4 kHz to 10 kHz range). Thetympanic lens is designed to achieve the ultimate goal of improvinguser's hearing while minimizing any adverse effects resulting from theplacement of the tympanic lens on the tympanic membrane.

At high frequencies, e.g., between approximately 4,000 Hz andapproximately 10,000 Hz, the energy required to directly drive theeardrum through a tympanic lens is approximately an order of magnitudeless than the energy required to drive an audio speaker because theactuator/reed displacement required is an order of magnitude less thanthe displacement required to push air to create an equivalent dB SPL(i.e., an equivalent perceived sound level to the listener) in a typicalair conduction hearing aid. In air conduction hearing aids, thisincreased energy drain results in an increased battery drain and adecrease in the time between replacing or recharging a battery. In orderto obtain the same battery life and dynamic range in an air conductionhearing aid, it would be necessary to use a larger battery, which isconsidered undesirable.

Direct drive of the eardrum results in an improvement in gain at higheraudio frequencies. In direct drive, the reed and umbo move nearly inunison and the efficiency of power transfer between them is high.Furthermore, the smallest type of balanced armature transducer can beused for direct drive, since the displacement involved is very small,and this typically allows lower reed mass and better high-frequencytransducer performance. In contrast, in air-conduction hearing aids, thetransduction path from reed motion to umbo motion is less efficientbecause it involves many more steps: The reed moves a speaker diaphragm,which drives air in the ear canal, which in turn flexes the tympanicmembrane and applies force to the umbo. Power is lost in each step oftransduction (compressing of the canal air volume, flexing of the TM andcompressing of the back volume of the middle ear.). Furthermore,open-ear-tip hearing aids suffer even greater inefficiency because soundis radiated out of the ear canal, representing an additional power lossmechanism.). Larger receivers are typically used to increase soundoutput in air-conduction hearing aids, and these may have lowerhigh-frequency output.

Direct drive of the eardrum can also be used to reduce feedback. Whenthe umbo moves, some of its motion is translated to the TM, whichradiates sound back into the canal toward the microphone. However, theTM acts as an inefficient speaker and the back-radiated sound pressureis much lower than the equivalent pressure sensed by the subject via thedirect umbo drive. In contrast, in air-conduction hearing aids, the fullpressure delivered to the canal and sensed by the subject is radiatedtoward the microphone and will result in increased feedback.

Because of the increased efficiency and lower feedback, there is animprovement in gain at higher audio frequencies. The increasedefficiency enables a higher amplitude output at high frequencies, whichallows for a larger dynamic range between the softest sound that can beheard and the maximum output of the TMT. This larger dynamic rangeresults in higher achievable gain. The lower feedback allows foradditional stable gain before feedback.

One concern with the application of force to skin, including thetympanic membrane and, more specifically, the umbo, is the potential fordamage to the skin, including pressure sores. Such damage may be avoidedby, for example, limiting the applied pressure to ensure that theapplied pressure does not prevent blood from reaching the skin under theumbo platform. The tympanic lens is, therefore, designed to preventdamage to the tympanic membrane or other tissues in the ear canal. Thetympanic lens is designed to provide direct mechanical drive to thetympanic membrane without damaging that membrane or any tissue in theear canal. In practice, damage to the tympanic membrane may be preventedby limiting the pressure applied to the tissue of the tympanic membraneto a pressure which is less than the pressure which would cause thecapillaries in the tympanic membrane to collapse (e.g., 20 mmHg). Damagemay be further limited by providing a safety factor of, for example, 2×to prevent damage resulting from capillary collapse.

A second concern is the impact placing a tympanic lens on the tympanicmembrane could have on a user's natural hearing. While the tympanic lensdescribed herein is adapted to improve the user's hearing by driving thetympanic membrane directly, the tympanic lens is further designed tolimit any reduction in a user's natural hearing resulting from theplacement of the tympanic lens on the eardrum. The tympanic lens istherefore designed to minimize any reduction in air conduction hearingresulting from placing the tympanic lens in the ear canal and/or on thetympanic membrane. The tympanic lens is further designed to prevent anincrease in bone conduction hearing. The tympanic lens is furtherdesigned to prevent or limit autophony resulting from the placement ofthe tympanic lens on the tympanic membrane. Limiting the pressureapplied to the umbo and/or the mass of the elements in contact with theumbo may reduce bone conduction hearing and/or autophony.

They tympanic lens is designed to sit inside on the user's external earcanal in a manner which makes it easy to place and easy to remove,without surgery. The tympanic lens must remain in intimate contact withthe tympanic membrane through a range of movement, including, movementof the user's head. Movement of the user's head may be problematicbecause forces exerted on the tympanic lens by such movements may tendto pull the tympanic lens or elements of the tympanic lens away from thetympanic membrane. In one example, certain orientations of the user'shead may result in an increased gravitational pull on the tympanic lens,pulling the tympanic lens, or elements of the lens, away from thetympanic membrane. The tympanic lens must, therefore, be designed toaccount for such movements of the user's head. Similarly, some movementsof the tympanic membrane, such as the movement caused by a Valsalvamaneuver, may dislodge the tympanic lens or elements of the tympaniclens from the tympanic membrane if the tympanic lens is not designed toaccount for such forces. Thus, a tympanic lens according to the presentinvention is designed with features which hold the tympanic lens inplace against the tympanic membrane and are designed to assist inkeeping the tympanic lens in place even when external forces act to pullor push the tympanic lens away from the tympanic membrane.

In addition to remaining in place on the tympanic membrane, the tympaniclens includes a drive portion which is adapted to move the tympanicmembrane in response to signals applied to the tympanic lens. Since thedrive portion is not rigidly attached to the chassis of the tympaniclens, and is adapted to move freely with respect to that chassis, it isimportant to include design features which will provide a bias force tohold the drive portion in contact with the tympanic membrane in thepresence of the gross forces discussed above, including gravitationalforces and forces applied through the tympanic membrane itself (e.g.,forces resulting from a Valsalva maneuver).

Tympanic lens 100 may be held in place by the mechanical features of thetympanic lens including the perimeter platform. Additionally, thephysician or user may apply a fluid, such as mineral oil, to help tohold the tympanic membrane in place. The fluid assists in holding thetympanic lens in place because of the surface tension and viscous dragforces between the fluid and elements of the tympanic lens, such as theumbo lens and the perimeter platform. The viscosity of the fluid will beimportant to the amount of viscous drag forces holding the tympanic lensin place.

The total force exerted by the tympanic lens on the tympanic membrane isthe combination of a number of different forces, including forcesgenerated by elements of the tympanic lens and external forces. Theforces generated by elements of the tympanic lens include the staticbias force generated by the bias springs and the dynamic drive forcegenerated by the movement of the reed when current is applied to themicroactuator. External forces include the force of gravity, forcesresulting from the movement of the users head and forces resulting fromthe movement of the tympanic lens.

During normal operation, microactuator 140 exerts very small amounts ofdynamic force on umbo UM in order to achieve the displacement requiredfor amplification. For example, in a normal ear, with approximately 80dB of sound pressure level (SPL) at the tympanic membrane TM, umbo UMhas an average peak to peak displacement of approximately 20 nm(nanometers) at 1 kHz. In the invention, an umbo UM displacement ofapproximately 20 nm may be achieved when microactuator 140 exerts a peakdynamic force of approximately 6 (micro Newton). In one embodiment ofthe invention, a sound pressure of 120 dB SPL may be simulated byapplying a peak force of approximately 0.6 millinewtons to the umbo. Inembodiments of the invention, tympanic lens 100 vibrates the tympanicmembrane over a spectrum of amplification that extends from a minimumrange of 125 Hz to 10,000 Hz. Frequencies outside of this range may alsobe transmitted but the efficiency at such frequencies may be reduced. Inembodiments of the invention, tympanic lens 100 transmits amplifiedsound by vibrating the eardrum through direct contact.

The tympanic lens is designed to maintain the umbo lens in contact withthe tympanic membrane while allowing the umbo platform to move inresponse to movement of the reed. Thus, the tympanic lens canaccommodate gross movements, caused by, for example, movement of theusers head or movements of the tympanic membrane, while maintaining theumbo platform in contact with the tympanic membrane to allow reedvibrations to be transmitted directly to the tympanic membrane.

Tympanic lens 100 does not contain a power source and is activated onlywhen BTE 110 is switched on and light tip 120 is inserted into the earcanal EC. tympanic lens 100 includes photodetector 120 which convertsthe light pulses it receives from the light tip 120 into electricalsignals which activate microactuator 140 to transmit vibrations to theumbo UM through direct contact. In embodiments of the present inventionboth signal and power are transmitted to tympanic lens 100 by lightreceived from light tip 120.

In embodiments of the invention, tympanic lens 100 is in direct contactwith the umbo UM of tympanic membrane TM through umbo platform 160. Umboplatform 160 may be made up of umbo lens 220 and drive post 200. Themass of umbo platform 160 should be as small as possible since increasesin mass will reduce the high end frequency response of the system.

Umbo lens 220, which may be made from, for example, Parylene, such as,for example Parylene C, and may be custom fit to the umbo UM of theindividual ear anatomy of a user. Micro forces applied through umbo lens220 act to directly vibrate the tympanic membrane when those forces areapplied to umbo platform 160. Umbo lens 220 is preferably made of amaterial which is stiff enough to spread the pressure exerted by drivepost 200 along the entire surface of the umbo UM which is contacted byumbo lens 220. An optimal Parylene umbo lens may have a thickness ofapproximately 18 microns.

It may, therefore, be advantageous to utilize an umbo lens having alarge area in contact with the umbo to spread the forces applied bydrive post 200 across a large section of the umbo, thus reducing theapplied pressure on the tissue of the umbo. The distribution of pressureis important to prevent damage to the umbo, such as pressure sores. Inorder to prevent damage to the umbo tissue, the pressure exerted by theumbo lens may be limited to less than approximately 20 millimeters ofmercury (mmHg). A large umbo lens is also beneficial because itincreases the area of an oil layer between the umbo lens and the umbotissue, thus helping to hold the umbo lens in place on the umbo viaforces due to surface tension and viscous drag. However, a large umbolens is disadvantageous in that it will result in a loss of airconduction hearing by blocking a section of the tympanic membrane. Alarge umbo lens may also result in an undesirable increase in boneconduction hearing (which may result in an increase in autophony). It istherefore advantageous to limit the overall area of the umbo lens,provided that the decreased area does not result in other problems, suchas an increase in the pressure applied to the tissue beyond that whichis safe, or a decrease in hydrostatic forces which results in the umbolens detaching from the umbo.

In practice, an optimal umbo lens may have a diameter of betweenapproximately 2.5 millimeters and approximately 3.5 millimeters. Inembodiments where the umbo lens is not round, that diameter may bemeasured at the widest point of the umbo lens. Further, in practice, anoptimal umbo lens may have an area of between approximately 4.9 squaremillimeters and approximately 9.6 square millimeters.

For an umbo lens having an area of approximately 4.9 square millimeters(the smallest optimal umbo lens) a force of 6 millinewtons wouldtranslate to a pressure of approximately 9.3 millimeters of mercury(mmHg), a safety factor of 2 with respect to a pressure of 20 mmHg. Foran umbo lens having an area of approximately 7 square millimeters, aforce of 6 millinewtons would translate to a pressure of approximately6.5 millimeters of mercury (mmHg). For an umbo lens having an area ofapproximately 9.7 square millimeters (the largest optimal umbo lens) aforce of 6 millinewtons would translate to a pressure of approximately4.6 millimeters of mercury (mmHg).

An adhesive, such as Masterbond UV15X-6Med-2 or Epotek OG116-31 may beused to attach the umbo lens to the drive post. The adhesive may befurther used to extend the effective length of the drive post. Theadhesive may be use to extend the length of the drive post by buildingup the adhesive in the umbo lens prior to inserting the drive post. Theadhesive may further be used to extend the effective length of the drivepost to ensure that the drive post meets the umbo at a substantiallyright angle in order to ensure efficient transmission of vibrations fromthe microactuator to the umbo.

For reasons set forth above, it may be advantageous to limit the amountof adhesive used to connect the umbo lens to the drive post in order tolimit the effective mass of the drive post, umbo lens, adhesivecombination, thus reducing the effective mass on the umbo. Reducing theeffective mass on the umbo both improves high frequency output andimproves (decreases) bone conduction hearing changes and autophony.

Drive post 200 may be bonded to umbo lens 220 by, for example, adhesiveMasterbond UV15X-6Med-2 or Epotek OG116-31. Drive post 200 may be usedto couple mechanical vibrations generated by microactuator 140 to umboUM. It would be advantageous to minimize the mass of drive post 200 inorder to minimize the effective mass of the umbo platform. Drive post200 is designed to be positioned over the center of the umbo when thetympanic lens is properly positioned.

Microactuator 140 may use an electromagnetic balanced armature design.Microactuator 140 includes a reed extending through an opening at adistal end of the microactuator and a membrane surrounding the openingthrough which the reed extends. In the microactuator, the reed isconnected to the drive post. In one example, a reed with a thickness ofapproximately 0.006 inches (approximately 150 micrometers) is used.

The outer casing of the microactuator may act as a flux return path forthe motor and may be constructed of a nickel iron alloy to facilitatethe return flux path. The microactuator, including the outer casing maybe coated in order to prevent corrosion or discoloration. Themicroactuator may be coated in, for example, Parylene and/or gold toprevent corrosion or discoloration. The outer casing of themicroactuator may be a stainless steel material which does not act as aflux return path but protects the microactuator from corrosion ordiscoloration.

The diaphragm may be positioned to prevent water, oil and debris fromentering the microactuator through the hole where the reed extends fromthe distal end of the microactuator. The diaphragm is preferably madefrom a material, for example, urethane or silicone, which is flexibleenough to allow the distal end of the reed to vibrate withoutcompromising its efficiency.

In the tympanic lens, light energy is converted by the microactuatorinto movement of the reed, which transmits those movements through theumbo platform to the tympanic membrane. Microactuator 140 may bedesigned such that the force exerted by the reed may be approximately2.7 Newtons per Ampere of input current. In the tympanic lens, the inputcurrent supplied by the output of the photodetector which receives lightenergy from an emitter located in the light tip.

The system may be designed such that the output of the laser/emitter maybe adjusted in steps in order to adjust the static current applied tothe microactuator and the dynamic force applied to the tympanicmembrane, increasing the maximum output of the system. For example, thesystem may be designed such that 1 dB increase in light results in 1 dBincrease in average current applied to the microactuator which allows anincrease in the dynamic force applied to the tympanic membrane of up to1 dB SPL (Sound Pressure Level). For users with significant hearingloss, the higher levels of emitter output would result in higher maximumavailable force that can applied to the tympanic membrane through themovement of the reed to provide a higher maximum output of the system.

Because the tympanic lens must accommodate macro movements, such as, forexample, movements caused by Valsalva maneuver, the tympanic lensincludes a hinge connecting the microactuator to the chassis. In oneembodiment, the hinge is formed by the bias springs, which connect themicroactuator to the chassis. In addition to connecting themicroactuator to the chassis and acting as a hinge, the bias springsalso provide the bias force necessary to keep the microactuator in placethrough macro movements. Because the tympanic lens must also accommodatemicro movements of the reed without moving the microactuator in responseto those micro-movements, the tympanic lens is designed to maximize theinertia of the microactuator in response to movements of the reed.

The tympanic lens may, therefore, be designed to allow macro movementsthrough a hinge design while increasing the inertia of the microactuatorin response to movements of the reed by positioning the hinge at theopposite end of the microactuator from the drive post 200. A largerdistance between the springs and the drive post 200 increases its momentof inertia (resistance to movement) with respect to forces exerted onthe microactuator by movements of the reed, which improves efficiency byhelping to keep the microactuator stationary as the reed vibrates.

The hinge may secure the microactuator so that it is at an anglerelative to the chassis. The angle is achieved by adjusting the distancebetween the reed of the microactuator and the umbo of the tympanicmembrane. The angle is design to ensure that the microactuator does notinterfere with the anatomy after placement while also allowing movementas a result of the various forces exerted on the tympanic lens, forexample, a Valsalva maneuver. The angle is designed to ensure that thebias force remains in the appropriate range. The angle of themicroactuator with respect to the chassis is, however, limited by theneed to pass the tympanic lens through the ear canal and position it onthe tympanic membrane. In embodiments of the invention, the angle of themicroactuator with respect to the chassis is a function of the desiredbias force, the anatomical fit and the insert ability. In embodiments ofthe invention, the microactuator may be designed to form an angle ofbetween zero and 15 degrees with respect to the plane of the chassis.

In one embodiment of the invention, tympanic lens 100 employs dual biassprings (which may also be referred to as torsion springs) 180 toconnect microactuator 140 to chassis 170 and bias microactuator 140towards tympanic membrane TM. When properly mounted, microactuator 140should be at an angle of between approximately 0 and approximately 15degrees with respect to a plane through the chassis with the umboplatform 160 positioned to contact the umbo. Bias springs 180 may beused to position microactuator 140 at an appropriate angle to thechassis.

While in situ in the ear canal EC, microactuator 140 is positionedalmost upside down when the user is standing or sitting. Bias spring(s)180 provide sufficient force to counter the weight of microactuator 140,providing a positive net force, towards tympanic membrane TM to ensuregood coupling between umbo lens 220 and umbo UM.

While the Bias spring(s) must be sufficiently strong to overcome theforce of gravity and keep umbo lens in position on the umbo, they shouldalso, for the reasons set forth herein, not be so strong that the umbolens causes damage to the tympanic membrane. Additionally, excessivespring force may degrade the audio characteristics of the tympanic lens,or increase autophony. Therefore, bias springs 180 may, in someembodiments of the invention be designed to be very soft springs. Inembodiments of the invention, bias spring(s) 180 may be designed toexert at least 0.8 millinewton of force on the umbo UM, when gravity isworking against bias spring(s) 180. Bias spring(s) 180 may also bedesigned to exert a force which is less than the force applied on thetympanic membrane TM by the tensor tympani muscle. Bias spring(s) 180may also be designed such that microactuator 140 moves with the tympanicmembrane TM and does not impede its natural movement.

In certain orientations of the user's head, the bias force from biasspring(s) 180 and the weight of the microactuator become additive.Tympanic lens 100, including the force exerted by the bias springs may,therefore, be designed such that that the maximum total force exerted ontympanic membrane TM is less than 6 millinewtons. Tympanic lens 100,including the force exerted by bias spring 180, is designed such thatthe maximum total force exerted on tympanic membrane TM results in apressure of less than the minimum venous capillary return pressure.Tympanic lens 100, including the force exerted by bias spring 180, maybe further designed such that the maximum total pressure exerted on thetympanic membrane through the umbo lens is less than 20 millimeters ofMercury. Tympanic lens 100, including the force exerted by bias spring180, may further be designed such that that the maximum total forceexerted on tympanic membrane TM is less than 3 millinewtons. Tympaniclens 100, including the force exerted by bias spring 180, may be furtherdesigned such that the maximum total force exerted on tympanic membraneTM is less than the force exerted by 10 mmHg air pressure on tympanicmembrane TM.

In one embodiment of the invention, the spring constant of bias spring180 is approximately 1.5×10-5 Newton meters per radian.

Bias springs 180 are arranged to allow the umbo platform to move atleast 0.3 millimeters. Bias springs 180 are arranged to allow the umboplatform to move a distance which ensures that the umbo platform willcontinue to be in intimate contact with the tympanic membrane when theuser performs a Valsalva maneuver. Bias springs 180 are arranged toallow umbo platform to maintain contact with the tympanic membrane whenchanges in pressure between the inner and outer ear, (e.g., as a resultof sneezing, burping or flying), cause the tympanic membrane to move upto approximately ¼ mm. Bias springs 180 may therefore be designed toenable the umbo platform to maintain contact with the umbo through ¼ mmof movement.

Bias springs 180 may also be designed to minimize the force, pressure,displacement and impedance presented to the umbo without losing contactwith the tympanic membrane. Minimizing force, displacement and impedanceat the umbo may also minimize the effect of the tympanic lens on boneconduction hearing and autophony.

The position of the tympanic lens in the ear canal when properly placedresults in gravity pulling the microactuator away from the TM in manysituations. Therefore, the minimum bias force required to be exerted bythe bias spring is the force required to offset the force of gravity onthe microactuator. In one embodiment, the microactuator may have a massof approximately 120 milligrams, in which case, the bias force requiredto keep the umbo lens in contact with the tympanic membrane is at least0.8 millinewtons. In this embodiment, the bias springs may be designedto provide a bias of at least 0.8 milliNewtons.

In embodiments of the invention, a tympanic lens may have resonant oranti-resonant frequencies when positioned in the user's ear canal, on ornear the user's tympanic membrane. These resonant and/or anti-resonantfrequencies may be located within the range of frequencies which thetympanic lens is designed to transmit to the user, such as, for example,the range of audio frequencies. Such resonant and/or anti-resonantfrequency responses may, in some embodiments, result in unwanteddistortion, amplification and/or attenuation of the audio signaltransmitted to the user by the tympanic lens. In embodiments of theinvention, it would be advantageous to introduce a damping materialand/or damping element between the tympanic lens chassis and themicroactuator to reduce the effect of the resonant and/or anti-resonantfrequency responses. In embodiments of the invention, it would beadvantageous to introduce a damping material and/or damping elementbetween the tympanic lens chassis and the microactuator to move theresonant and/or anti-resonant responses to frequencies which do notimpact the performance of the tympanic lens, such as, for example, outof the range of audible frequencies.

In embodiments or the invention, the inclusion of a bias spring mayresult in or act to increase unwanted harmonic vibrations in thefrequency range of interest (e.g., between 125 Hz and 10,000 Hz in oneembodiment of the invention). One mechanism for limiting or eliminatingthose vibrations is the inclusion of a damper in the tympanic lens. Inembodiments of the invention, the damper is designed to limit or preventunwanted harmonic vibrations by damping the motion of the bias spring.In these embodiments, the damper acts by taking away the free motion ofthe bias spring(s), damping resonance and anti-resonance behavior of thesystem. In embodiments of the invention, inclusion of damper within thespring will increase the overall stiffness of the spring and shift thefrequency response of the system forward, to frequency ranges that areless critical for speech audibility. The damper may also make the biassprings stiffer than they would be without damping at low frequencies(e.g., below 4 KHz). The inclusion of a damper in the tympanic lens mayalso result in the reduction or elimination of autophony caused byunwanted harmonic oscillations of the system. In embodiments of theinvention, the inclusion of a damper in the tympanic lens may alsoresult in the reduction or elimination of the TM damping (i.e., overallreduction in a user's audibility) induced by placement of the tympaniclens on the eardrum. In embodiments of the invention, a damper may beinserted into the tympanic lens between the chassis and themicroactuator to dampen resonant and/or anti-resonant behavior resultingfrom, for example, the movement of the microactuator and/or componentsof the microactuator with respect to the chassis.

The damper may be a material applied to the bias springs to dampen themotion of the bias springs at low frequencies (e.g., frequencies of lessthan 500 Hz or frequencies of less than 4 KHz). The materials used tocoat or fill the bias spring may be chosen to have a characteristicstorage modulus and loss modulus. The storage modulus describes thematerials solid, elastic properties. The loss modulus is related toviscosity and gives the material the ability to dissipate energy as heatthrough internal friction as the material is deformed.

In embodiments of the invention, the materials used to coat or fill thebias spring may be chosen to have a storage modulus in the range ofapproximately 100 Pascals (Pa) to approximately 200,000 Pascals (200kPa). In embodiments of the invention, the materials used to coat orfill the bias spring may be chosen to have a storage modulus in therange of approximately 8,000 (8 kPa) to 30,000 Pascals (30 kPa). Inembodiments of the invention, materials used to coat or fill the biasspring may be chosen to have a storage modulus of approximately 10,000Pascals (10 kPa).

In embodiments of the invention, the materials used to coat or fill thebias springs may be chosen to have a loss modulus in the range of200,000 Pascals (200 kPa) to approximately 20,000,000 Pascals (20 MPa).In embodiments of the invention, the materials used to coat or fill thebias springs may be chosen to have a loss modulus in the range of1,000,000 Pascals (1 MPa) to approximately 10,000,000 Pascals (10 kPa).In embodiments of the invention, the materials used to coat or fill thebias springs may be chosen to have a loss modulus of approximately6,000,000 Pascals (6 MPa).

The viscosity of the coating material may act as an energy lossmechanism in the damper. The damping material used may be a viscoelasticmaterial or a material such as silicone or a silicone gel. The dampingmaterial may be a material which becomes stiffer or more viscous as thevibration frequency of the tympanic lens 100 increases. The dampingmaterial may be a material which provides greater damping at lowerfrequencies and lower damping at higher frequencies. Specific classes ofviscoelastic materials include Newtonian, dilatant, rheopectic andthixotropic.

In embodiments of the invention, the bias spring may be damped toprevent the system from oscillation at resonance or anti-resonancefrequencies. Such oscillations could divert energy from signaltransmission, reducing the amount of drive to the umbo lens at theresonant frequency. In particular, bias spring 180 may be damped toprevent oscillation at a resonant (or anti-resonant) frequency of thesystem, such as, for example approximately 500 Hz. Bias spring 180 maybe damped by coating the coils of bias spring 180 in a damping material,such as, for example, silicone or a silicone gel. Bias spring 180 may bedamped by filling the coils of bias spring 180 in a manner that createsa damper, which may be a plug of damping material, in the center of thecoils of bias spring 180. Bias springs 180 may be damped by adding adamper which prevents side to side motion of microactuator 140 withrespect to chassis 170. A damper may be adapted to stiffen lateral modesof vibration or any other mode of vibration which reduces the energywhich reaches the tympanic membrane. Damper 185 may be designed to dampa critical vibration mode of the system which shows up betweenapproximately 400 Hz (resonance) and approximately 600 Hz(anti-resonance).

In selecting an appropriate damping material for the present invention,the moduli (Young's modulus E, shear modulus, etc.) of a material areoften treated as a complex number, mathematically. That is, the complexmodulus E* will have real and imaginary components: E*=E′+iE″ (wherei²=−1). In the present invention, E′ is the storage modulus and E″ isthe loss modulus. The loss modulus is related to viscosity by:E″=ωη=2πη×frequency, where η is the dynamic viscosity in Pascal-seconds(or Centipoids, cP). 1 cP=0.001 Pa-s=1 mPa-s. In embodiments of theinvention, the viscosity of the damping material can be in the range of100 mPa-s (a light oil) through 100,000 mPa-s (a paste) and higher. Inembodiments of the invention, the viscosity of the damping material canbe in the range of approximately 1,000 Centipoids to approximately10,000 Centipoids. In embodiments of the invention, a damping materialwith a viscosity of approximately 5000 Centipoids.

As used herein, the terms damp, damping, damped, dampened refer to thefunction and/or properties relating to decreasing the amplitude of anoscillating system.

In embodiments of the invention, a tympanic lens, comprises: a chassis;a perimeter platform connected to the chassis; a microactuator connectedto the chassis through at least one bias spring positioned at a proximalend of the microactuator; a damper attached to the at least one biasspring; and an umbo platform attached to a distal end of themicroactuator. In embodiments of the invention the tympanic lens furthercomprises a photodetector mounted on said chassis and electricallyconnected to the microactuator through at least one wire. In embodimentsof the invention, the damper comprises a viscoelastic material incontact with the at least one bias spring. In embodiments of theinvention, the viscoelastic material comprises silicone. In embodimentsof the invention, the viscoelastic material comprises a silicone gel. Inembodiments of the invention the at least one bias spring comprises aseries of coils and the viscoelastic material fills the center of thecoils. In embodiments of the invention, the at least one wire passesthrough the center of the series of coils at a right angle to the seriesof coils.

Embodiments of the present invention include a method of controllingunwanted vibration in a tympanic lens, wherein the tympanic lenscomprises a chassis, a perimeter platform connected to the chassis, amicroactuator connected to the chassis through at least one bias spring,the method comprising the step of: damping the motion of the at leastone bias spring. Embodiments of the invention the at least one biasspring is coated in a damping material. In embodiments of the invention,the damping material is a silicone material. In embodiments of theinvention, the at least one bias spring comprises a series of coils andthe damping material fills the center of the coils.

In embodiments of the invention a tympanic lens, comprises: a perimeterplatform; a microactuator connected to the perimeter platform through atleast one biasing element positioned between the microactuator and theperimeter platform; a damper attached to the at least one biasingelement; and an umbo platform attached to a distal end of themicroactuator. In embodiments of the invention, the perimeter platformis connected to the microactuator at a proximal end of themicroacutoator. In embodiments of the invention, the tympanic lensfurther includes a chassis connected to the perimeter platform and themicroactuator. In embodiments of the invention, the biasing element is aspring. In embodiments of the invention, a photodetector is mounted onthe chassis and electrically connected to the microactuator through atleast one wire. In embodiments of the invention, the damper comprises aviscoelastic material in contact with the at least one bias spring. Inembodiments of the invention, the viscoelastic material comprisessilicone. In embodiments, of the invention the at least one bias springcomprises a series of coils and the viscoelastic material fills thecenter of the coils. In embodiments of the invention, the at least onewire passes through the center of the series of coils at a right angleto the series of coils.

Embodiments of the present invent include a method of controllingunwanted vibration in a tympanic lens, wherein the tympanic lenscomprises a perimeter platform connected to a microactuator through atleast one biasing element, the method comprising the step of: dampingthe motion of the at least one biasing element. In embodiments of theinvention, the at least one biasing element is a spring. In embodimentsof the invention, the at least one bias spring is coated in a dampingmaterial. In embodiments of the invention, the damping material is asilicone material. In embodiments of the invention, the at least onebias spring comprises a series of coils and the damping material fillsthe center of the coils.

The photodetector is connected to a PC board located on the grasping tabby a first set of wires. The PC board is, in turn, connected to bondpads on the back of the microactuator through a second set of wires. Thesecond set of wires may be, for example, 48 Gauge wires. The second setof wires and the routing thereof is selected to minimize thecontribution the second set of wires makes to the overall springconstant of the system. The size of the second set of wires is selectedto be as small as possible in order to minimize any contribution to thespring constant of bias springs 180. The second set of wires are routedthrough the coils of bias springs 180 to minimize any contribution suchwires might make to the spring constant of bias spring 180. Theconnection between the PC board and the microactuator is made with 30micron (48 Gauge) wires, which are routed through the center of biasspring 180 to minimize the spring stiffness of the spring added by theconnector wires.

One consideration in selecting the size and routing of the second set ofwires is the effect of such wires on the force applied to themicroactuator by the combination of the second set of wires and the biassprings. The size and routing of the second set of wires should bechosen to minimize the contribution of the second set of wires to thetotal effective spring constant of the second wire bias springcombination. In one embodiment of the present invention, the size androuting of the second set of wires should be selected to limit thecombined spring constant of the springs and the wires to less thanapproximately 2.0×10⁻⁵ Newton meters per radian.

The Chassis is the support structure for the tympanic lens. It isdesigned to support the microactuator and umbo platform while bridgingthe tympanic membrane. The chassis is further designed to bridge thetympanic membrane without touching it. In embodiments of the invention,the chassis supports the photodetector, microactuator and othercomponents and circuitry without touching any part of the tympanicmembrane, including raised portions such as the short process (which mayalso be referred to as the lateral process) of the malleus. The chassisis designed to be oriented in a manner which prevents contact with theshort process when the tympanic lens is properly positioned in the ear.The chassis is also designed and oriented to prevent the chassis fromtouching the manubrium of the malleus and any other structures orregions on the tympanic membrane. The chassis is designed to bepositioned at least ½ millimeter above the surface of the eardrum at itsclosest point to allow the eardrum to move without contacting thechassis.

Each chassis may be individually designed and manufactured for specificusers. The chassis size and the relationship between the chassis and theperimeter platform drives design of individual chassis, including itsheight above the tympanic membrane.

The chassis provides a stable platform for the microactuator to workagainst through bias springs 180 when pressing the umbo platform againstthe surface of the tympanic membrane.

Tympanic lens 100 is intended to remain in the user's ear for a longperiod of time and may be constructed using biocompatible materials.Long term stability of tympanic lens 100 is achieved through the use ofa perimeter platform which provides support and stability to tympaniclens 100. The perimeter platform may be customized to match theindividual user's ear anatomy. The perimeter platform may be customizedto fit along the sulcus of the tympanic membrane TM. When properlypositioned on the ear of a user, the perimeter platform may rest on theportion of the ear canal wall surrounding and immediately adjacent totympanic membrane TM. The perimeter platform may be made of a materialsuch as Parylene. The perimeter platform may be designed to have athickness sufficient to support the tympanic lens while not being sothick that it kinks when bent. The perimeter platform may beapproximately 18 microns thick.

The perimeter platform is designed not to touch the tympanic membranebut to provide a support structure, along with the chassis, to suspendthe microactuator over the tympanic membrane such that only soundproducing features touch the tympanic membrane. The perimeter platformis generally designed not to touch the pars tensa (portion of eardrumunder tension). In some designs, the perimeter platform may overlapregions of the tympanic membrane up to a distance of approximately ½millimeter.

The perimeter platform includes a region known as the sulcus platform atan anterior medial end of the perimeter platform. The sulcus platformsits in sulcus (curved portion of bony canal at the medial end of thecanal which intersects with tympanic membrane). The sulcus platformserves to anchor the anterior end of the tympanic lens in the Ear Canal,preventing it from moving deeper into the ear canal or from moving awayfrom the ear canal. The sulcus platform may act in concert with the umbolens and the remainder of the umbo platform preventing the tympanic lensfrom moving away from the tympanic membrane and back out into the earcanal.

The perimeter platform may be designed to be sufficiently flexible tocompress as it passes through the ear canal and expand when it reachesthe tympanic membrane and is positioned in place. Expansion of theperimeter platform when placed at the distal end of the ear canal mayassist the tympanic lens to remain in place by pressing the perimeterplatform against features of the ear canal.

The Perimeter platform includes openings at its proximal and distal endswhich allow air to past through the perimeter platform to reach thetympanic membrane, thus allowing natural sounds to reach the tympanicmembrane. Openings in the proximal and distal ends of the perimeterplatform which facilitates air conduction hearing, even with thetympanic lens in place.

The width of the perimeter platform is customized for each user toensure that the tympanic lens can be safely and successfully passedthrough the ear canal. The height of the perimeter platform may involvea tradeoff between height and surface area. The surface area wouldpreferably be made larger to facilitate holding the tympanic lens inplace (through, for example, hydrostatic force), however the heightwould preferably be made smaller to facilitate the need to insert thetympanic lens through the ear canal, which can require a smaller heightto get through narrow regions and around obstacles. The height of theperimeter platform may be optimized to be between approximately 1millimeter and approximately 1.5 millimeters tall.

Tympanic lens 100 may be held in place by one or more of surfacetension, fit, and/or friction. The surface of the perimeter platform isadapted to hold the tympanic lens in place through surface tension. Whenproperly placed and maintained there is a layer of oil present betweenthe perimeter platform and the surface of the ear canal covered by theperimeter platform. The tympanic lens is kept in place at least in partby the surface tension/hydrostatic force of the oil acting to hold theperimeter platform on the ear canal surface.

In embodiments of the invention, tympanic lens 100 may be held in placeby the fit between tympanic lens 100 and features of the ear canal EC.In embodiments of the invention, tympanic lens 100 may be held in placeby mechanical interlocking between features of tympanic lens 100 andanatomical features of the user's ear canal. In embodiments of theinvention, tympanic lens 100 may be held in place by mechanicalinterlocking between perimeter platform 150 and curvature of the earcanal such as the anterior bulge and the angle of the deep sulcus regionwith respect to the canal lateral to the sulcus.

In embodiments of the invention, tympanic lens 100 may be held in placeby frictional interaction between elements of tympanic lens 100 andfeatures of the user's ear canal, for example, perimeter platform 150may be positioned to push against elements of the user's anatomy whileumbo platform 160 pushes against umbo UM, preventing tympanic lens 100from moving laterally with respect to tympanic membrane TM.

Oil, such as Mineral oil, may be applied to the ear canal EC to createsurface tension between the portions of the ear canal wall adjacent thetympanic membrane and the perimeter and umbo platforms. Oil can createsurface tension between the surface of the perimeter and umbo platformsand the skin of the ear canal that keeps the perimeter and umboplatforms in place. Such surface tension may be used to, for example,keep tympanic lens 100 in place and coupled to tympanic membrane TM.Such surface tension may also be used to keep umbo lens in place andcoupled to umbo UM. Oil may also be used to keep the perimeter platformin place without actually touching the skin of the ear canal, allowingskin tissue to migrate out from under the umbo platform and perimeterplatform without interference. Oil may be used to allow skin tissue tomigrate out from under perimeter platform and umbo platform withoutdisplacing the tympanic lens.

The photodetector 130 is comprised of a semiconductor material which hasbeen processed to convert photonic energy into electrons, generatingcurrent, for example Silicon, Gallium Arsenide or Indium GalliumArsenide. The semiconductor material has been bonded to a carrier, forexample, ceramic or PCB material, in a manner such that the anode andcathode can be connected to the microactuator through the PC board andwires. The semiconductor and carrier are protected with a covering toensure that there is a clear light path from the emitter to thesemiconductor and that the assembly is protected from mechanicalhandling and exposure to fluids found in the ear canal, for examplewater, mineral oil, or cerumen. The covering may be a plastic housing,epoxy or silicone coating, Parylene or a combination of those materials.

The photodetector may be protected from fluid (e.g., sweat) ingress byfront-coating or dip coating it in a soft silicone material, such as,Nusil Med-4086, Nusil Med-6345, or Shin-Etsu KE-109 Silicone followed bya separate Parylene outer coating. The use of this layered process isimportant because the soft silicone material relieves stress and willnot damage wire bonds on the photodetector when it expands or deformsdue to thermal, mechanical or chemical processes, including swellingupon exposure to fluids (such as sweat, water or oil). Siliconeencapsulants can also provide strong adhesion to the underlyingmaterials (photodetector and carrier) to prevent fluid ingress andbuildup that could compromise reliability. In addition, the layeredstructure further prevents fluid ingress and buildup. The Parylene outercoating may be a thin coating of approximately 18 micrometers thicknessof Parylene C. The Parylene thickness may span the range ofapproximately 3 micrometers to 50 micrometers. The photodetector may becoated in a manner which leaves a frosted dome over the front (lightsensitive portion) of the photodetector. In addition to improving theresistance to fluid ingress, the addition of a Parylene outer coatingprovides a surface against which a health care professional may push,using a probe, when inserting the tympanic lens into a user's ear canalwithout damaging or destroying the silicone coating or thephotodetector. Finally, the addition of a Parylene outer coating isadvantageous because it limits light reflection off the surface of thephotodetector, making it easier for the health care professional to seewhen placing the tympanic lens using an external light source.

The soft silicone may also be encapsulated with an alternate, hardconformal coating materials rather than Parylene. Example hard-coatmaterials include adhesives such as Epotek OG116-31 epoxy, Polytec EP653epoxy, and silicones such as Shin-Etsu SCR-1012 and SCR-1016 and DowCorning OE-7670 and OE-7662.

The grasping tab is positioned adjacent to the Photodetector. It is usedby the physician to hold the tympanic lens as it is placed into the earcanal using, for example, a forceps. The grasping tab extends in a planewhich is parallel to the chassis to facilitate placement. Device staysin line with grasped with forceps as inserted. The grasping tab includesa removal ring which is used to facilitate easy removal using a bent orright angle pick.

FIGS. 7D, 7E, and 7F are circuit diagrams of the tympanic lens,including a photodetector and microactuator. In one embodiment of theinvention, the design has constant value parameters, and is driven by aninput signal composed of a DC signal and an AC signal. In one embodimentof the invention, the constant value parameters fall into the ranges:

C_(PD) (junction capacitance of the PD) ranges from 4 to 7 nF (6 nF isnominal)

C_(EXT) (added capacitance) ranges from 0 to 15 nF (0 is nominal)

R varies from 270 to 330 Ohms (300 is nominal)

L varies from 20 to 26 mH (24 mH is nominal)

The DC components vary based on the input power to the photodetector andfall into the ranges:

W _(pd) (DC light power) ranges from 0.3 to 3.0 mW (0.875 mW is nominal)

Ī_(pd) (DC PD current) ranges from 0.1 to 1 mA (0.3 is nominal)

V _(pd) (DC PD voltage) varies from 27 mV to 330 mV

The AC components are dependent on the signal level and can vary from 0to full scale DC:

{tilde over (W)}_(pd) (AC light power) ranges from 0 to 3.0 mW

Ĩ_(pd) (AC PD current) ranges from 0 to 1 mA

{tilde over (V)}_(pd) (AC PD voltage) varies from 0 to 1V

The grasping tab is positioned adjacent to the Photodetector. It is usedby the physician to hold the tympanic lens as it is placed into the earcanal using, for example, a forceps. The grasping tab extends in a planewhich is parallel to the chassis to facilitate placement. Device staysin line with grasped with forceps as inserted. The grasping tab includesa removal ring which is used to facilitate easy removal using a bent orright angle pick.

In a hearing aid system according to the present invention, sound isdetected by microphones in the BTE and converted to electrical signalswhich are passed through signal processing circuitry. The output of thesignal processing circuitry is transmitted through a cable to a lighttip positioned in a user's ear canal. At the light tip, the electricalsignals are converted to light signals, which are transmitted throughthe user's ear canal to the tympanic lens described herein.

In one embodiment of the invention, sound waves received bymicrophone(s) 310 are converted into electrical signals, digitallyprocessed, amplified and sent to light tip 120 through cable 260. Lighttip 120 houses emitter 290, which may be, for example, a laser diode.Emitter 120 converts the electrical signal containing the amplifiedsound information into light pulses 40. When light tip 120 is insertedinto ear canal EC and BTE 110 is switched on, light pulses 40 shine ontophotodetector 130 on tympanic lens 100. Photodetector 130 converts lightpulses 40 back into electrical signals which drive microactuator 140 oftympanic lens 100 to transmit sound vibrations to umbo UM.

Light tip 120 may be inserted and removed from the ear canal daily bythe user.

In one embodiment of the invention, the Audio Processor consists of abehind the ear unit (BTE) and an attached Ear Tip. The BTE is anexternal device worn behind the ear of the user. The BTE housesmicrophones, a digital signal processor and a rechargeable battery. TheBTE also includes a programming button to allow the recipient to switchto different programmed memory settings and a programming connector toallow connection of the BTE to an external computer running, forexample, fitting software. The Light tip houses a laser diode and isconnected to the BTE with a cable.

In operation of the BTE converts sound into electrical signals, whichare passed to the light tip where the electrical signals are convertedinto light pulses. In the BTE however, the sounds waves are received bythe microphones and converted into electrical signals, which aredigitally processed, amplified and sent to the light tip through acable. The laser diode in the light tip converts the electrical signalscontaining the amplified sound information into light pulses. The lightpulses are transmitted to the tympanic lens, at which point they areconverted back into electrical signals which drive the microactuator andcouple mechanical vibrations directly to the umbo of the tympanicmembrane. The BTE is designed to allow health care professionals toadjust the brightness of the light transmitted by the light tip.

The laser diode used in the Ear Tip is custom made in order to maximizethe efficiency of light conversion. The laser diode is a VCSEL (verticalcavity surface emitting laser) and operates at infra-red wavelength of850 nm. The BTE uses electrical pulses to drive the laser and allows thehearing health professional to adjust the light intensity as part of thefitting process.

In order for the system to work and the recipient to perceive soundamplification, the light pulses transmitted from Ear Tip need to bereceived by the tympanic lens and therefore the laser and thephotodetector need to be generally aimed at each other. In order toachieve this in variable ear canal anatomies two key steps are taken: 1)the laser includes a diffuser, which provides greater insensitivity tomisalignment by providing a broad and diverging beam pattern and 2)during the manufacturing of the Ear Tip, the laser is aimed at thephotodetector using anatomical information from the silicon impressionof the full ear canal.

The housing for the light tip is a custom mold made to fit individualear anatomy with comfort while maintaining approximately 3-4 mmseparation between the laser and the photodetector photodiode of thetympanic lens. Materials used in the manufacture of the light tipinclude acrylic, silicone and biopore.

The taper tube acts as a strain relief for the cable as it enters thelight tip and may act as a handle for user's who are removing the lighttip from the ear canal. The taper tube also acts as a safety feature toprevent the light tip from being inserted too deep into the ear canal.

The cable is bent to follow the anatomy of the ear canal and the tragus.When the light tip is properly positioned, the cable will come out abovethe tragus and below the crus helix of the user's ear.

The light tip include built in emitter supports and taper tube supportswhich provide platforms to hold the emitter and taper tube while theyare being glued in place. These topographical features allow an operatorto accurately position the emitter and taper tube and hold them in placeduring the process of gluing them to the light tip. The emitter is heldin a horseshoe shaped feature which includes a flange to assist it inaligning properly. The taper tube is held in a glue ring with a toothfeature to control its lateral and medial position during the gluingprocess.

In addition and similar to rechargeable hearing aids a BTE charger isprovided to the recipient to help replenish the battery inside the BTE.The charger may have connectivity, such as, for example WiFi, to allowit to automatically upload data from the BTE while the BTE is beingcharged. That data may be uploaded to, for example, the user's healthcare provide or to the BTE manufacturer. The charger may be furtheradapted to automatically change its power output depending on the timeof day, user profile etc. Such changes in power output may also be usedto modulate the range of the charger. While in the charger, the BTE mayalso send periodic fuel gauge profiles to the charger. The indicatorlights on the charger may be used to indicate what profile data is beingtransmitted from the BTE to the charger. Further, the charger may beadapted to automatically dim or even turn off LED indicator lights onthe charger based on the time of the day so that the LED light does notinterfere with the sleep patterns of the users.

In embodiments of the invention, a BTE includes a battery, a circuitboard, a charging coil, a back iron (ferrite disk) and a spacer. Thesecomponents are arranged such that the charging coil, back iron andspacer (the charging elements) are mounted on the battery, which is, inturn, mounted on the circuit board. The charging coil is adapted toreceive electromagnetic energy from a charger, which is then used torecharge the battery. The back iron is a ferrite disk which focuses andconcentrates the electromagnetic field from the charger.

In the event that moisture, such as sweat, gets into the BTE, it maycreate an electrolyte which provides a path for ferriteelectro-migration in the presence of electromagnetic fields. In theevent of such moisture ingress, ferrite may migrate through theelectrolyte from the ferrite disk to the charging coil, reducing oreliminating the effectiveness of the coil. There is also potential fordamaging the internal electronics due to the ferrite migration. Inembodiments of the invention, ferrite electro-migration may occur in thepresence of battery voltage, which may cause ferrite electro-migrationfrom the ferrite disk to the battery.

In embodiments of the invention, the spacer is placed between thebattery and the ferrite disk to isolate the battery case from theferrite disk and/or to position the coil to maximize the efficiency ofthe transfer of energy between the charger and the BTE. This spacer maybe made of plastic and is mounted to the battery using an adhesive. Inorder to prevent electro-migration of the ferrite to the charging coil,the charging coil, ferrite, spacer combination may be conformal coated.The conformal coating may be, for example, a conformal coating using anorganic coating material, such as Hysol. The conformal coating preventselectro-migration of ferrite from the backing iron to the charging coil.

In embodiments of the invention, the battery, circuit board combinationmay be separately coated, using, for example, Parylene C. Separatelycoating the battery, circuit board combination ensures that there is noelectro-migration of ferrite to the battery or circuit board.

In embodiments of the invention, the charging elements and the batteryare separately coated to prevent magnetic fields within the coating fromcausing electro-migration under the coating. In embodiments of theinvention, the portion of the spacer attached to the battery is notcoated since the conformal coating will not stick to the adhesive usedto attach the spacer to the battery. In embodiments of the invention,the edge of the coil, ferrite and spacer are coated, sealing the sidesand top but not the bottom of the charging elements (antenna stack).This side and top coating ensures that there will be noelectro-migration along the edge of the charging elements (antennastack) between the backing iron and the coil.

In embodiments of the invention, a hearing aid device comprises: anantenna stack having a top, sides and a bottom, the antenna stackcomprising: a coil antenna having a first and second side, the firstside of the coil antenna forming the top of the antenna stack; a backingiron having a first and second side, the first side of the backing ironbeing attached to the second side of the coil antenna; and a spacerhaving a first and second side, the first side of the spacer beingattached to the second side of the backing coil and the second side ofthe spacer forming the bottom of the antenna stack; a battery stack, thebattery stack comprising: a rechargeable battery having a first andsecond side, the first side of the rechargeable battery being attachedto the second side of the spacer; a printed circuit board attached tothe rechargeable battery; a conformal coating material covering the topand sides of the antenna stack sealing the top and sides of the antennastack from moisture ingress; a second coating material covering the topand sides of the battery and the printed circuit board, sealing thebattery stack from moisture ingress. In the embodiments of theinvention, the conformal coating material comprises an organic coatingmaterial. In embodiments of the invention, the conformal coatingmaterial comprises Hysol. In embodiments of the invention, the secondcoating material comprises Parylene.

Embodiments of the invention include a method of preventing ferritemigration in a hearing aid including an antenna stack and a batterystack wherein the antenna stack sits on the battery stack, the methodcomprising the steps of: conformally coating the top and sides of theantenna stack using a conformal coating material; and separately coatingall the surfaces of the battery stack using a separate material.

In embodiments of the invention, an adhesive cover is used to preventmoisture ingress into the CS45 data connector. The adhesive coverprevents moisture from getting into the CS45 connector and causing theconnector pins from shorting. The use of a disposable adhesive covereliminates the need for a thicker cover which may interfere with thehousing cover.

In embodiments of the invention, a fitting software is provided to thehearing health professional to customize the prescription to therecipient's hearing profile. The Fitting (ELF) software is used by thehearing health professional to program and customize the Audio Processorto the individual hearing profile. In addition to the ELF software, thefitting system includes a laptop personal computer (PC), a HiPro 2 box[GN Otometrics A/S] and programming cables for each BTE.

In embodiments of the invention, the ELF software includes a Lightgrammeasurement, which is used to calibrate the output of the hearing systemof the present invention in equivalent acoustic pressure units (dBSPL).The output of prior art air conduction hearing aids are typicallycharacterized with the use of a 2 cc coupler and an ear simulator, whichare intended to represent an average ear. Since the output of thepresent systems is mechanical sound vibrations through direct contact tothe umbo, a calibration is needed to represent these vibrations inequivalent terms to acoustic sound pressure. To this effect, during thefitting session a user's unaided pure tone acoustic thresholds aremeasured using conventional audiometric techniques and recorded in ELF.Subsequently, aided pure-tone thresholds are measured using theLightgram, where tones are generated in the Audio Processor, played backand responses are recorded as the light based thresholds. Using thesetwo sets of pure tone threshold data, ELF computes a calibrationfunction which equates the light stimulus of the present system to anequivalent sound pressure level at the tympanic membrane. In practice,the calibration is determined for each ear by measuring the soundpressure required to achieve threshold of hearing at standardaudiometric frequencies between 125 Hz and 10,000 Hz, then measuring theoutput level of the CHD (the Lightgram) to achieve the same thresholdlevel. In this way, not only is the system calibrated but the maximumequivalent pressure output (MEPO) can also be determined. The MEPO ofthe CHD is determined by adding the remaining CHD headroom at thresholdto the acoustic sound pressure delivered at threshold to determine themaximum output of the system at each of the standard audiometricfrequencies.

For example, in one embodiment of the invention, a subject requires 65dB SPL to reach the acoustic threshold during a hearing test at 2000 Hz.The same subject, when fitted with the CHD requires an output at a powerlevel that is −55 dB relative to the full scale output to reach the sameperceptual threshold at 2000 Hz. The MEPO can be determined by adding 65dB SPL (acoustic threshold) and 55 dB (additional headroom to reach fullscale output), or a MEPO of 120 dB SPL.

In order to present the natural sound quality to hearing aid users, theselection and combination of hearing aid parameters have to be arrangedand ordered in a way which optimizes those settings for each individualuser. Hearing aid devices currently available require user interventionwhen programming the device. Since user intervention is required, thenumber of available programs may be limited because users cannotgenerally keep track of more than four programs at a time. This limitednumber of options may make it difficult for a user to program theoptimal parameters based on the environment they are in. In addition, itmay be difficult for a user to know which program is active and it mayrequire trial and error to get to the right target program, resulting infrustration and poor sound quality. Limiting the number of availableprograms based upon the need for user intervention, instead of thesystem capabilities (e.g. storage capacity) results in a sub optimalsolution.

Some hearing devices have mitigated this problem by providing differenttypes of tones and/or differing numbers of beeps to indicate particularprograms and assist the user in programing their devices. Howeverdepending upon the current program type and voice prompts. Though usefulthis type of feedback still requires the user to actively participate inselecting the optimal program parameters. In addition, many users do notwant it known that they are wearing hearing aids so social stigmaassociated with the user using program buttons in public in order to getto the right parameter selection may deter them from changing theprogram settings, even where the result is suboptimal hearing.

In the present invention, the hearing aid may be automaticallyprogrammed, without active user intervention. In the present invention,wirelessly connecting the hearing aid to an external device, such as asmart phone, allows the hearing aid to use the location sensor built inthe connected device to activate parameters based on external parameterssuch as the user's location. Alternatively, a GPS sensor may also beembedded in the hearing aid device to offer location based parameterprogramming. With a GPS enabled location device, either in the hearingaid or an associated device, the software would be able to gatherexternal data to program the hearing aid for operation based upon thosefactors, for example, whether a user is in a car and the speed of thecar. The system may then select specific programs or settings tooptimize the user's experience, such as, adjusting a noise reductionalgorithm to reflect the added wind noise that might be experienced by auser in a car. Location devices may also be used to determine whether auser is indoors or outdoors and activate settings or programs in thehearing aid automatically based upon those parameters. As anotherexample, if the user is in the mall or movie theater, the appropriateparameter selection can be made to give them optimal sound quality. As afurther example, if the user is in concert hall, the music program canautomatically be selected without user intervention.

In embodiments of the invention, hearing aid programs and parameters mayalso be updated based upon events on the user's calendar. For example,if the user is scheduled to have a business meeting in his/her calendar,the device can create a record of that and automatically put it in aquite mode during the meeting.

In embodiments of the invention, a request to stream real time audiomusic may result in the programs and parameters of the hearing aid beingadjusted to automatically select the music program selection withoutuser intervention and revert to the previous program selection when theaudio stream disconnect request is received.

In embodiments of the invention, configuring the hearing aid device intoa hands free listening device during an active phone conversation, mayresult in the hearing aid automatically mode switching to a directionalmicrophone set up and selection of a program which includes appropriatenoise reduction and fast feedback cancellation. Once the user hangs upthe call, the hearing aid may automatically revert back to its originalprogram selection.

In embodiments of the invention, the user's external environment may besensed by the hearing aid and/or associated device and the programs andparameters automatically adjusted as the user's environment changes. Thehearing aid automatically selecting the appropriate program or parameterbased on the environment the user is in. As an example, wirelesscommunication programs may be disabled or turned off when the hearingaid or associated device senses that the user is on an airplane, by, forexample, sensing the presence of an iBeacon. In one embodiment, aniBeacon application running on the connected device will sense theiBeacon and signal the hearing device to put itself in the airplanemode. As a further example, temperature sensors in the hearing aidand/or associated device could be used to determine if the user issitting in a sauna or taking a cold shower and the hearing aid programsand parameters adjusted accordingly.

In embodiments of the invention, physical characteristics of the usermay be sensed by the hearing aid and/or associated device and theprograms and parameters automatically adjusted based upon thosecharacteristics. For example, a hearing aid device may have an embedded3D accelerometer to determine the activity level of the user and theprograms or parameters could be automatically selected if the patient issitting up, sleeping, running and/or walking.

In embodiments of the invention, sensors on the hearing aid and/orassociated device may include location sensors such as GPS and/or aniBeacon receiver. In embodiments of the invention, the associated devicemay include one or more special applications. In embodiments of theinvention, the hearing aid device may include a software algorithm toautomatically enable and select different programs or parameters basedon inputs such as location, iBeacon inputs, user selected programs suchas audio streaming or Calendar events.

It is generally desirable that hearing-aid systems be reliable, with nosystem failures. Thus, it is desirable to perform preventativemaintenance on regular basis before any system failure. In addition, itwould be useful to be able to predict when preventative maintenance willbe required in order to plan service resource needs. There are manymoving parts in the system and it will be desirable to predict thefailure modes and life cycle counts of these components so that timelyservice and/or replacement could be performed.

The device software actively monitors the hearing aid system, collectingdata on the system components. The collected data may then be comparedto thresholds stored in device memory and the user alerted when thesubsystems and/or components of the devices need to be replaced. Theuser may also clear alerts. Alerts may also be sent to the user's healthcare provider or to the manufacturer. Usage related information can alsobe communicated to a remote server which gathers and processes usagerelated information from multiple hearing aids.

In one embodiment of the invention, the hearing aid system collects abroad range of data which may be used to predict failure of the systemand provide alerts when components of the system need to be replaced orrepaired. Data collected by the hearing aid system may include:

1. A manufacturing timestamp indicating the date the system, and/or acomponent thereof was manufactured.

2. A placement timestamp indicating the date a tympanic lens was placedin the user's ear.

3. A removal timestamp indicating the date a tympanic lens was removedfrom the user's ear.

4. One or more fitting timestamps, indicating the date the hearing aidsystem was first programed for the user and/or the date of the firstaudiogram and/or lightgram for that user.

5. One or more lightgram timestamps, indicating the date of eachsubsequent lightgram.

6. A count of the number of times the hearing aid system is programed.

-   -   a. This count may be a count of the number of times the        communication accelerator adaptor (“CAA”) connector is used.    -   b. This count may be used to predict failure of the CAA        connector by comparing the count to the life limit of the CAA        connector insertions

7. A time stamp log of all over the air programing (“OTAP”).

8. A log of all the number of times the system is turned on and theduration of use.

9. A log of the number of times the system is placed into standby modeand the durations of those standby times.

10. A count of the number of times the BTE is recharged and the durationof those charging cycles.

11. A count of the number of times the BTE is placed in its chargingslot.

-   -   a. This count may compared against a specification and used to        predict a failure based upon wear and tear.

12. A log of the laser current settings (e.g. LC=6 . . . 1) and a countof the number of times those settings are changed

13. A count of the number of times the laser current exceeds its maximumspecified value.

14. A count of the number of times the laser is turned off and on.

-   -   a. This count may be a count of the number of times the laser        current driver is turned on.    -   b. This count may be compared against a specification and used        to predict a failure of the laser current driver

15. A count of the number of times a light tip is inserted into theuser's ear.

-   -   a. This count may be based upon:        -   i. A feedback measurement reading;        -   ii. A battery temperature reading from the fuel gauge; or        -   iii. A battery temperate reading of the wireless chip    -   b. Light tip insertion count may be compared against a        specification on the life limit of the light tip insertion and        used to predict failure of the light tip.    -   c. Light tip insertion count may be compared against a        specification on the life of the light tip connection wire and        used to predict failure of the light tip connection wire.

16. A count of the number of motor post movements

-   -   a. This count may be compared against a specification on the        life limit of the motor post and used to predict motor post        failure.

17. A timestamp indicating the time the battery is replaced;

18. A timestamp indicating the time the battery is manufactured;

19. A count of the number of times the battery is recharged.

20. A record of the battery temperature;

21. A record of the battery over temperature conditions;

22. A count of the number of times the battery current exceeds itsspecified limit; and

23. A count of the number of times the battery voltage is less than itsspecified limit.

24. A count of the number of times the rocker switch is depressed

25. A record of which programs are selected by the user and the numberof times each program is selected.

26. A record of the volume settings selected by the user and the numberof times those settings are changed.

-   -   a. This count may be based upon the number of activations of the        from the Rocker switch    -   b. This count may be based upon data from a device, such as a        cell phone, wirelessly connected to the hearing aid system.

27. A record of the frequency of application of oil to the user's ear

28. A record of the quantity of oil applied to the user's ear (e.g.number of drops)

29. A record of the person dispensing the oil into the user's ear.

30. A record of the number and length of Bluetooth low energy (“BLE”)connection sessions.

31. A record of the number and length of Audio streaming sessions.

32. A record of the number and length of Audio codec selections.

The hearing aid system may also include a list of life limit thresholdsfor various actions in its memory. As an example, the hearing aid systemmay include the life limit on battery recharge cycles in its memory. Asthe data described above is collected, the collected data is comparedagainst relevant stored data, such as, life limit thresholds stored inmemory. When the collected data reaches a predefined limit, such as alife limit threshold, an alert may be sent to indicate that the hearingaid system, or a component of that system is in need of maintenance orrepair. These alerts may be sent directly to the user, the user's healthcare provider, the hearing aid system manufacturer or any combination ofthe above. In the event that the alert is sent to the user, it may berepeated at predefined intervals until cleared by the user.Alternatively, the hearing aid system may be designed such thatspecified hearing aid alerts can only be cleared by the health careprovider or the manufacturer. In addition, alert types may be userprogrammable. Such user programmable alert alternatives include, voiceprompt, audible beep and pop up messages on a connected device. Thehearing aid system may send both preventative and critical maintenancenotifications. Connected device apps can convert the alerts in calendarevents upon receiving.

Of particular interest in hearing aid systems is tracking andmaintenance of the battery, particularly in hearing aid systems usingrechargeable batteries. In the hearing aid system described herein thereare multiple functions performed which are related to battery trackingand maintenance.

The hearing aid system may range check the battery temperature from thefuel gauge and alert the user if the hearing aid system has been exposedto the out of bound conditions, such as extreme temperature. Once thebattery temperature is exposed to the out of bound conditions, thehearing aid system will shut off predetermined elements of the system toprevent damage to the system. Before shutting off the system, the systemmay set a “Device Check” flag, which may be reset by a technician afterthey have thoroughly checked the device and/or replaced the battery.

The hearing aid system may also monitor the battery for voltageconditions which are indicative of remaining battery life during acharge cycle. Under low battery conditions, predetermined elements ofthe system may be disabled and enabled again when the battery voltage ishigh enough. Alternatively, the hearing aid system could recommendcertain settings, profiles or usages to the user in order to extend theremaining battery life. These settings, profiles and usages could bemodified by the system as the battery ages and its capacity is reduced.

The hearing aid system may also monitor the battery temperature. Achange in battery temperature could indicate that the battery has beenremoved from its charger. If the battery is removed from the chargerwhen the hearing aid system is not being used, the hearing aid systemmay be put into deep sleep mode to conserve power. The hearing aidsystem may further broadcast an audible signal to indicate its locationto the user. A change in battery temperature may further indicate achange in the position of the BTE relative to the user or the charger.If the battery temperature indicates that the BTE is no longer on theuser's ear or in the charger, the hearing aid system may be put into adeep sleep mode to preserve battery life. Alternatively, or in addition,the BTE may be programed to broadcast a signal, for example, every threeseconds, to assist the user in locating the BTE.

The fundamental problem with short distance wireless communication iscross-interference and interoperability. In devices using short distancewireless communication, either the controller or the peripheral canconnect and communicate with any other device as long as they use thesame RF frequency band and link layer protocols. As multitude of thesedevices operate in close proximity, cross channel interference andinteroperability becomes an issue. Traditionally user intervention isrequired to selectively associate with the devices of interest. Inaddition, extensive authentication and encryption algorithms are used toprotect the integrity of the data and device identification. Since theshort distance devices all operate in close proximity, selectivelyassociating with the device of interest becomes a very complicatedprocess.

One solution to these issues in a hearing aid system would be the use ofa pairing button to pair the BTE and charger. However, pairing buttonstake extra space on the device, cost extra money and introducereliability issues. In addition, such switches require the user toremember to push the pairing button, which is not desirable from an easeof use perspective. Alternatively, extensive encryption andauthentication methods may be used to ensure proper pairing but thosemethods add to development and validation cycles while introducingunnecessary complexity to the system.

In embodiments of this invention, the traditional problems are solved byusing two different low power wireless communication techniques toassociate and communicate among devices of interest selectively withoutthe need for user intervention, or the use of a pairing button orextensive protocol re-engineering. In the present invention, when thehearing-aid device is dropped into the slot of the charger base, itautomatically triggers a sequence wherein low power communicationprotocols are used to associate the hearing aids exclusively with thatcharger base, without the need for user intervention, a pairing button,or complex authentication schemes. In addition, embodiments of thepresent invention automatically locate a local charger when a user walksinto a room and alerts the user if the user leaves the room withoutbringing the charger along.

In one embodiment of the present invention, illustrated in the flowdiagrams of FIGS. 20 and 21, a short-distance wireless chargingtechnique is used to associate the hearing-aid device to the chargerbase without the need for pairing. In embodiments of the invention, thisis accomplished using a low distance wireless communication techniquethat is initiated upon insertion of the BTE into the charger base slot.The association of the hearing-aid device to the associated charger iscritical to make sure the right hearing-aid device is being charged andprofiled on the status indicators. This invention also uses low powerwireless communication between the hearing-aid and the charger base toassociate, authenticate, exchange device profile and status informationwhile in the charger base. The system may also be adapted to perform twoway communication from the charger base to the device. The presentinvention is adapted to eliminate the problem of a hearing-aid devicesitting in one charger base can inadvertently communicate to anothercharger base in close proximity to the charger base.

In the present invention, the insertion of a BTE into a charger is usedto automatically trigger association of the inserted BTE with thecharger base. The charger software is adapted to keep track of aplurality of BTEs and to identify left and right devices. A unique ID isgenerated every time a BTE is dropped into the charger base, reducing oreliminating the chance of charging a BTE in a nearby charging base. Whenthe BTE is dropped in the slot of the charger base, an 8-bit uniquerandom ID is generated using an OOSK method. This unique ID is onlyassociated with that base and is communicated to the BTE using anextremely low power protocol to avoid cross-communication to any otherdevice. The extremely low power protocol is adapted to preventcommunications beyond 1 cm. When the BTE is dropped in the slot in thecharger base, upon detection in the charger base, the device uses thelowest transmit TX power settings to avoid cross-interference with otherchargers in the close proximity.

In the present invention, a low power RF power cycle modulation sequencemay be used to encode charger base ID and exchanged through the wirelesscharging coil. The BTE demodulates the unique encoded ID transmitted bythe charger and then uses this ID in a wireless communication protocol,such as a low power Bluetooth Low Energy (“BLE”) protocol, to advertiseitself on the network. In embodiments of the invention. suitablewireless communication protocols may include, for example WiFi, Zigbeeor other wireless protocols. The charger base is continuously scanningand listening to find BTEs that have same ID. Once a B having the properID is identified, it is associated with the charger. The association isachieved by low power on/off sequence to generate a unique ID as opposedto using BLE protocol to associate devices. Once a BTE is associatedwith a charger base, the system switches over to low power BLE protocolto communicate between the charger and BTE. Such communication mayinclude communication of the battery profile of the BTE, whichinformation may be used to allow the user to see the battery statuswhile the device is sitting in the charger base. The association may beended as soon the BTE is removed from the charger.

In one embodiment of the invention, illustrated in the flow diagram ofFIG. 21A the introduction of a hearing aid into the charger is sensed bythe charger because of a fluctuation in the charger magnetic field. Thisfluctuation is sensed as a change in the I_SENSE signal. The hearing aidsenses that it has been placed into a charger by sensing a heart beatsignal from the charger and signals its presence by cycling on and off.The hearing aid then sends the charger a packet structure, including apreamble and, assuming the correct preamble is sent, the chargeridentifies the hearing aid as being a valid hearing aid (i.e., a hearingaid that can be charged). If the hearing aid is not identified as beinga valid hearing aid, the charger will not initiate charging and turnsoff. The authentication process takes approximately 5 seconds. Once thehearing aid is authenticated, the charger can read the state of charge(SOC) status along with the battery voltage and temperature.

In embodiments of the invention, when there is no device in the slot,the firmware on the charger is put in deep standby to conserve power.The charger system may be adapted to wake up from the interrupt when aBTE is dropped in the slot. In embodiments of the invention, there isprogrammable hysteresis built in the charger base to ensure thatmomentarily device drops in the slot and/or momentarily removal of thedevice from the slot do not trigger the charger to change status (e.g.wake up or go into standby mode). In embodiments of the invention, thecharger may be configured such that it will continuously broadcast itslocation in the room or office.

In embodiments of the invention, the BTE may be associated with anexternal device such as a smart phone and the smart phone may be alertedwhen a charger is nearby so that the user is given an option to use thecharger while there. In embodiments of the invention, the smart phonemay also assist the user in finding a nearby charger if requested by theuser. Other alerts, either directly by the charger or through the smartphone may include alerting the user that they are leaving he chargerbehind, the BTE is fully charged, the BTE is in the charger or the BTEis being removed from the charger. In addition, the smart phone may beused to define a geolocation based on a user's profile and adjust thepower output of the charger beacon mode to a smaller or larger geofence.In embodiments of the invention, the charger may be connected to aremote data source, such as a cloud based server. By connecting to theremote data source, the charger may transmit data from the remote datasource to the BTE, including, for example, firm ware updates. Thecharger may also transmit data from the BTE to the remote data source,including, for example, data logs showing data collected from the BTE.

In embodiments of the invention, a charger is responsible for chargingtwo BTE modules. The Charger oscillates a coil which transfers energy tothe BTE coil and charges the device. Firmware within the charger willdisable/enable the oscillation; detect if a BTE has been placed on thecharger; communicate with the BTE to find out the state of charge; anddisplay the battery level or fault conditions to a user using theexternal LEDs.

The state diagram illustrated in FIG. 23 shows the logic flow of theCharger FW. The charger starts of in the IDLE state, when an item isplaced the charger waits for a message for 5 seconds (MSG WAIT). Afterthe 5 seconds it transitions to a fault state or charging statedepending if a valid message was received. The charger then remains inthe charging state, except for when it requests (REQ) an update from theBTE every 10 minutes. When a full charge criteria has been met for over20 minutes the charger transitions into full state. While full thecharger transitions to an RCV state every 10 minutes for 10 seconds toallow for an update from the BTE. If a device is removed and any pointthe charger will transition to an idle state.

In embodiments of the invention, the charger charges the BTE byoscillating a PWM signal at 744 kHz. This signal induces anelectromagnetic field on the coil which transfers energy to thereceiving coil on the BTE. The PWM signal is toggled on for 10 ms andoff for 190 ms, resulting in a 5% duty cycle. When the PWM is on, an ADCsignal [I_SENSE] can detect if an object, such as a BTE is placed intothe charging bin. A level of 80 mV on the I_SENSE will indicate thepresence of a BTE. Once detected it has to drop below 64 mv in order tobe detected as off, this prevents jumping between on and off states. Thecharger allows 5 seconds for authentication process to complete. After 5seconds, if a valid message was received, the charger will continuecharging, and LED status will indicate state of charge to a user. If avalid message is not received after 5 seconds, charging will bedisabled, and an error status will be indicated by blinking 4 LEDs.

In embodiments of the invention, communication with the BTE is initiatedby the charger. It is the BTE's task to respond with an appropriatemessage. When the BTE is first placed in the charger it will startsending state of charge and voltage readings. After the first sequencethe charger will request an update every 10 minutes. The chargerrequests an update from the BTE by disabling the PWM signal for 500 msthen enabling it back on. This will be received by the BTE on theCHARGER_ON_L pin. It will cause the BTE to toggle states between standbyand charging. When the BTE goes to charging state it will send asequence of updated state of charge and voltage messages. The BTE sendsa message, by toggling the REFLECT pin. This will be received by theCharger on the ADC [I_SENSE] line. The BTE sends a 32 bit message in thefollowing format: 0xAz 0xdddd 0xA5, where 0xAz is the preamble thatindicates a start of transmission, ‘z’ indicates a nibble notifying whatvalue is sent (1 for %, 2 for V), 0xdddd is a 2 byte value. Followed by0xA5 to end the transmission. If a message does not meet the specifiedcriteria it will be ignored. It is important that the first and last bitsent is a 1, since this is how a start and end of transmission isdetermined.

Preamble Description Example 0xA1 battery state of charge 0xA10060A5:SOC = 96% message 0xA2 battery voltage message 0xA20F7CA5: V = 3964 mV

To determine if a 1 or a 0 bit is being transmitted an adaptivealgorithm used to find a threshold between a 1 and a 0. The algorithmtracks the maximum level, and the minimum level and finds the average ofthe two. The following table describes what is being communicated to theuser through the charger LED lights:

OFF Nothing in charger bin LED 1 fast blink Device has just been placedand authentication is taking place. First 5 seconds LED 1 SOC <= 33% LED2 SOC <= 66% LED 3 SOC > 66% LED 4 SOC >= 97% && SOC <= 100% && V > 41504 LED blink FAULT status.

When the BTL battery reaches full charge [SOC>=98% and V>=4180 mv] thecharger will charge for 20 more minutes, after which it will go to idlestate (PWM is driven at 5% duty cycle). The battery state will still bemonitored. Every 10 minutes the charge will be enabled for 10 secondswhich will allow the BTE to send an updated state of charge and voltagereading. If the voltage drops below 4100 mV charging will be resumed,otherwise the charger will go back to idle mode.

If a foreign device is placed on the charger and detected. The chargerwill wait 5 seconds to receive a message. If it does not receive amessage it will blink 4 LEDs to indicate a fault condition and thecharger state will go to idle.

In one embodiment of the invention, the charger software displays theLED status based on the current battery voltage, state of charge orcommunication state as follows: The first LED blinks when processordetection is in process and turn solid when the processor isauthenticated. The second LED turns solid when the battery state ofcharge is greater than 33%. The third LED turns solid when the batterystate of charge is greater than 66%. The fourth LED turns solid based onthe current battery voltage (BV), in mV, and/or state of charge (SOC),in percentage.

The Charger software blinks all four LEDs when it detects anon-communication state. The Charger software displays the LED status asnormal after a non-communication state has been cleared.

In one embodiment of the invention, the Charger software regularlyrestarts the watchdog timer before it's expired in, for example, 4seconds. In embodiments of the invention, the Charger software rangechecks the battery state of charge value. In embodiments of theinvention, the charger software monitors the current battery temperature(BT), in degrees Celsius, and/or the current battery voltage (BV), inmilli-Volts. The Charger software stops charging the processor when thesensing threshold level is less than 55 mV or after an adaptive chargingtimeout of up to 6 hours is expired.

In embodiments of the invention, the charger monitors the BTEtemperature as the BTE is being charged. In order to prevent overheatingthe BTE, the charger uses on/off cycling to limit the heat buildup inthe charger. In embodiments of the invention, the charger may usedifferent duty cycles, depending upon the state of charge of the BTE.For example, if the BTE is between a minimum voltage and a first voltage(e.g., between 3.0 and 3.5 volts) when placed into the charger, the dutycycle may be at a maximum value (e.g., 100%). In embodiments of theinvention, the BTE charge is prevented from going below the minimumvoltage by turning the BTE off until it can be recharged when it gets tothe minimum voltage. If the BTE is within a first interim range ofvoltage (e.g., between 3.5 volts and 4.18 volts), the charging dutycycle may decreased to an interim value (e.g., 90%). Once the BTEreaches its target charging voltage (e.g., 4.18 volts), the charging maycontinue in phases, with Phase 1 being a first duty cycle (e.g., 75%)for a first period (e.g., 10 minutes). Phase II may be a second dutycycle (e.g., 50%) for a second period (e.g., 10 minutes) and Phase IIIbeing a third duty cycle (e.g., 25%) duty cycle for a third period(e.g., 10 minutes). During each of these phases, the temperature iscontinually checked to ensure that the battery is not overheating. Atthe end of the third phase the charging may be discontinued and the BTEbattery voltage monitored until the battery reaches a depleted state(e.g., 4.1 volts), at which time the charging process is restarted.

In embodiments of the invention, it may not be possible to rely oncontinuous communication between the charger to ensure proper chargingbut prevent overcharging. The charger may, therefore include a watchdogtimer which estimates a time to charge when the BTE is placed into thecharger and sets a maximum charge time based upon the measured charge.The maximum charge time is used to shut off the charger in the eventthat the charger and BTE lose communication during the charging cycle.In embodiments of the invention, a maximum charge time is used toprevent overcharging and/or overheating. In embodiments of theinvention, this maximum charge time may be, for example, six hours. Themaximum charge time may, however, be adjusted to take into account theactual state of charge of the battery. For example, in embodiments ofthe invention, if the battery is 50% charged when the BTE is placed inthe charger the max charge time would be reduced. In one embodiment ofthe invention, the max charge time would be reduced from six hours tofour hours.

Embodiments of the invention include a method of charging a rechargeablebattery in a hearing aid, the method comprising the steps of: detectingthe presence of a rechargeable hearing aid in a hearing aid recharger;generating a unique random ID in the charger; transmitting the uniquerandom ID to the hearing aid using an extremely low power protocol;demodulating the unique ID in the hearing aid; using the demodulatedunique ID in a low power protocol to advertise the hearing aid on anetwork which includes the charger; associating the hearing aid to thecharger when the charger which broadcast the unique ID receives thatunique ID from a hearing aid using a wireless protocol; using thewireless protocol to communicate between the associated charging stationand hearing aid; radiating power from the charger to the hearing aid;and ending the association when the hearing aid is removed from thecharger. In embodiments of the invention, the step of establishing thestate of charge of the associated hearing aid prior to radiating powerfrom the charger to the hearing aid. In embodiments of the invention,the charger waits a predetermined time after detecting a hearing aid inthe charger before transmitting the unique ID to the hearing aid. Inembodiments of the invention, the charger charges the hearing aid byoscillating a pulse wave modulation signal at 744 kHz. In embodiments ofthe invention, the pulse wave modulation signal is toggled on forapproximately 10 milliseconds and off for approximately 190milliseconds.

Embodiments of the invention include a method of charging a rechargeablebattery in a hearing aid, the method comprising the steps of: detectingthe presence of a rechargeable hearing aid in a hearing aid recharger;generating a unique random ID in the charger; demodulating the unique IDin the hearing aid; transmitting the unique ID back from the hearing aidto the charger; radiating power from the charger to the hearing aid; andending the association when the hearing aid is removed from the charger.Embodiments of the invention further include the step of establishingthe state of charge of the associated hearing aid prior to radiatingpower from the charger to the hearing aid. In embodiments of theinvention, the charger waits a predetermined time after detecting ahearing aid in the charger before transmitting the unique ID to thehearing aid. In embodiments of the invention, the charger charges thehearing aid by oscillating a pulse wave modulation signal at 744 kHz. Inembodiments of the invention, the pulse wave modulation signal istoggled on for approximately 10 milliseconds and off for approximately190 milliseconds. Embodiments of the invention further include the stepof transmitting the unique random ID to the hearing aid using anextremely low power protocol. Embodiments of the invention furthercomprise the step of using the demodulated unique ID in a low powerprotocol to advertise itself on a network which includes the charger.Embodiments of the invention further comprise the step of associatingthe hearing aid with the charger when the charger which broadcast theunique ID receives that unique ID from the hearing aid. In embodimentsof the invention, the charger and hearing aid are associated using aBluetooth protocol. In embodiments of the invention, the wirelessprotocol is used to communicate between the associated charging stationand the hearing aid. In embodiments of the invention, the wirelessprotocol is a Bluetooth protocol.

Embodiments of the invention include a method of charging a hearing aidbattery, the method comprising the steps of: inserting the hearing aidinto a charger; measuring the current charge level of the battery;charging the battery at a first duty cycle for a first period until thecharge level of the battery reaches a first predetermined level;charging the battery at a second duty cycle for a second period untilthe charge level reaches a second predetermined level, wherein thesecond duty cycle is less than the first duty cycle; charging thebattery at a third duty cycle for a first fixed period, wherein thethird duty cycle is less than the second duty cycle; charging thebattery at a fourth duty cycle for a second fixed period, wherein thefourth duty cycle is less than the third duty cycle; charging thebattery at a fifth duty cycle for a third fixed period, wherein thefifth duty cycle is less than the fourth duty cycle; and discontinuingthe charging until the battery charge reaches a third predeterminedvalue, wherein the third predetermined value is less than the secondpredetermined value.

In embodiments of the invention, physical models are made of the user'sear canal, including the lateral and medial ends of the canal and thetympanic membrane. Once those physical models are made, they may bescanned to create a digital model of the user's ear canal. Inembodiments of the invention, the physical model of the user's ear canalmay be an impression of the ear canal taken by a healthcare provider. Inembodiments of the invention, the physical model may be multipleimpressions of all or portions of a user's ear canal which are scannedand the scanned data combined to generate the digital model of theuser's ear canal. In embodiments of the invention, the digital model maybe made directly by taking a scan of the user's ear canal using digitalscanning equipment and using the scanned data to generate the digitalmodel.

The digital model may be used to design the tympanic lens and light tipin the digital domain to ensure that the final products will fit intothe patient's ear canal and that the light tip is properly aligned whenplaced into the user's ear canal. The digital model may be further usedto design and properly positon a chassis alignment feature and aphotodetector alignment feature to form an alignment tool 700. Thedigital modeling step determines the optimal alignment of the chassis,the photo detector and the emitter. Once the positioning of those threecomponents is optimized, the digital model may be used to createappropriate alignment tools, including the photodetector alignmentfeature and the chassis alignment feature. In embodiments of theinvention, alignment may be accomplished in the digital domain using thedigital model. In embodiments of the invention, the alignment may beverified using the verification feature of FIG. 17.

The scanned data and digital model may then be used to size and positionthe chassis and photodetector. In embodiments of the invention, thegrasping tab and the posterior tympanic membrane plane may be used as abaseline. In embodiments of the invention, certain design rules are usedto ensure that the components of the tympanic lens are properlypositioned with respect to the anatomical features of the user. In oneembodiment of the invention, a 0.5 mm space is maintained between thechassis and the anterior sulcus. In one embodiment of the invention, a0.5 mm space is maintained between the chassis and the plane of thetympanic membrane TM. In one embodiment of the invention, the centeraxis of the chassis is designed to lie above the deepest point in theuser's umbo. In one embodiment of the invention, the chassis is designedto avoid interaction with any potential irritation areas like the ShortProcess and anterior bulge. In one embodiment of the invention, digitalproximity tools may be used to maintain appropriate relationshipsbetween the chassis and elements of the user's anatomy.

In embodiments of the invention, the photodetector positon may beestablished by using a fixed distance of, for example, 3.5 mm betweenthe face of the photodetector and the face of the emitter. The fixeddistance may, in some embodiments be between 3 and 9 mm. In embodimentsof the invention, both the emitter and the photodetector may be designedto be positioned along the superior ear canal axis to facilitateplacement of a connecting cord along the Tragus channel. Finally, oncethe positioning of the photodetector and emitter are determined,proximity tools may be used to confirm that there are no points ofinteraction between the photodetector and emitter and the user'sanatomy, including any anatomical features which would block or restrictthe transmission of light from the emitter to the photodetector. Inembodiments of the invention, digital alignment may be used to minimizedistance and offset the angle between the photodetector and the emitter.In practice, the photodetector is designed to be in line with theemitter axis to maximize energy transfer between the photodetector andthe emitter. During the manufacturing process, the photo detectoralignment feature and chassis alignment feature are used to align thephotodetector with the emitter and glue the photodetector in place onthe chassis.

In embodiments of the invention, once the relative positions of thephotodetector and chassis have been determined for a particular patient,the patient specific tympanic lens mold, photodetector alignment featureand chassis alignment feature may be manufactured for that patient. Inembodiments of the invention, these patient specific features may bedigitally modeled and the alignment of the resulting emitter andphotodetector checked in the digital domain before being manufactured.Alternatively, in embodiments of the invention, one or more molds may bemanufactured and used to align the resulting emitter and photodetectoras illustrated in FIG. 17.

In embodiments of the invention, two components, the tympanic lens andthe light tip are customized for the individual patient based upon animpression which is taken from that patient's ear canal. In embodimentsof the invention, the impression may be made by a physician. Theimpression may be taken using a material which hardens when poured intothe ear canal. In practice, the impression is inspected visually (forpresence of voids or air bubbles) and dimensionally (to confirm that thepatient's ear canal is large enough to accommodate the tympanic lens andlight tip. The impression may, thereafter, be scanned and a digitalmodel of the user's ear canal created by scanning the user's ear canalimpression. The digital model may, thereafter be used to create acavity, using, for example, 3D printing, resulting in the tympanic lensmold. In embodiments of the invention, the tympanic lens mold is coatedwith Parylene C through a vapor deposition process. The Parylene (nowmatching the shape of the ear canal) is then removed from the tympaniclens mold and may be trimmed to create the sulcus and the umboplatforms.

In embodiments of the invention, the tympanic lens mold may also be usedin the manufacture of the tympanic lens to properly position and affixthe photodetector to the chassis. In particular, an alignment toolincluding a chassis alignment feature and a photodetector alignmentfeature may be affixed to the tympanic lens mold and the chassispositioned in the tympanic lens mold using the chassis alignment featureto properly position the chassis. Once the chassis is aligned within thetympanic lens mold, the photodetector alignment feature may be used toproperly position the photo detector before it is glued to the chassis.In embodiments of the invention, the tympanic lens mold may be furtherused to properly position other components of the tympanic lens on thechassis. In embodiments of the invention, the chassis may be glued tothe sulcus platform, then the microactuator glued to the chassis, thenthe grasping tab glued to the chassis, followed by the placement andgluing of the photodetector to the chassis using the photodetectoralignment tool.

In embodiments of the invention, after the tympanic lens mold isfinished, an impression is made using the mold (with the same materialas the one used to take the original impression). This mold impressionis visually compared to the original impression to confirm absence ofsurface defects. This confirms that the tympanic lens mold was createdcorrectly.

Once the ear tip and tympanic lens are complete, the tympanic lens moldand the ear canal mold can be mated to form a complete model of theuser's ear canal. The complete model of the user's ear canal can then beused to verify that the manufactured ear tip and tympanic lens will beproperly aligned when placed in the user's ear. Specifically, themanufactured ear tip may be placed in the ear canal model and themanufactured tympanic lens in the tympanic lens model and the alignmentbetween the emitter in the manufactured ear tip and the photodetector onthe manufactured tympanic lens measured to confirm that they will beproperly aligned in the user's ear canal.

Embodiments of the invention include a method of manufacturing atympanic lens, the method comprising the steps of: creating a digitalmodel of at least a portion of a user's ear canal; manufacturing an earcanal mold using the digital model, wherein the ear canal mold includesa recessed portion wherein the recessed portion includes a model of atleast a portion of the user's medial ear canal, including the tympanicmembrane; manufacturing an alignment tool, including a chassis alignmentfeature and a photodetector alignment feature, wherein the chassisalignment feature and the photodetector alignment feature are unique tothe anatomy of the user; mating the ear canal mold and alignment tool;mounting a chassis in the ear canal mold using the chassis alignmentfeature to properly align the chassis in the ear canal mold; mounting aphotodetector to the chassis; and using the photodetector alignmentfeature to positon the photodetector on the chassis prior to gluing thephotodetector in place. In embodiments of the invention, the step ofcreating a digital model comprises the steps of: forming an impressionof a user's ear canal, including the user's tympanic membrane; anddigitally scanning the ear canal impression to create a digital model ofthe user's ear canal. In embodiments of the invention, digital data isused to size a chassis for the tympanic lens. In embodiments of theinvention, the chassis is sized for the user. In embodiments of theinvention, the ear canal mold is coated with a flexible material. Inembodiments of the invention, the flexible material is Parylene. Inembodiments of the invention, the chassis is placed into the mold, usingthe alignment tool to fix the position of the chassis with respect tothe tympanic membrane and features thereof. In embodiments of theinvention, the method further includes the steps of: gluing the chassisto the flexible material coating the mold; and cutting the flexiblematerial to create a perimeter platform and an umbo lens. In embodimentsof the invention, the flexible material is Parylene. In embodiments ofthe invention, the components are manufactured using 3D printing. Inembodiments of the invention, the method further comprises the step ofcreating registration markers to align the digital model with globalpredetermined coordinates of a digital working environment after thestep of digitally scanning the ear canal mold to create a digital modelof the user's ear canal. In embodiments of the invention, an origin ofthe global predetermined coordinates of the digital working environmentis positioned at the deepest point of the digital representation of thepatent's ear canal.

Embodiments of the invention include a method of manufacturing atympanic lens, the method comprising the steps of: forming mold of auser's ear canal, including the user's tympanic membrane; digitallyscanning the ear canal mold to create a digital model of the user's earcanal; using the digital data to size a chassis for the tympanic lens;manufacturing a chassis; manufacturing an ear canal mold, including arecessed portion with the anatomy of the user's medial ear canal,including the tympanic membrane; coating the ear canal mold with aflexible material; manufacturing an alignment tool, including a chassisalignment feature and a photodetector alignment feature; mating the earcanal mold and alignment tool; placing the chassis into the mold, usingthe alignment tool to fix the position of the chassis with respect to amodel of the user's tympanic membrane and features thereof mounting amicroactuator and photodetector to the chassis; and using thephotodetector alignment feature to positon the photodetector prior tofixing the photodetector in place. In embodiments of the invention, themethod further includes the steps of: affixing the chassis to theflexible material coating the mold; and cutting the flexible material tocreate a perimeter platform and an umbo lens. In embodiments of theinvention, the flexible material is Parylene. In embodiments of theinvention the components are manufactured using 3D printing.

Embodiments of the invention include a method of verifying the alignmentof a user unique light tip and tympanic lens, the method comprising thesteps of: manufacturing a light tip using a digital model of the lateralportion of the user's ear canal, the tympanic lens including an emitter;manufacturing a tympanic lens using a digital model of the medialportion of the user's ear canal, including the user's tympanic membrane,the tympanic lens including a photodetector; manufacturing averification fixture, the verification fixture comprising: an ear canalmold manufactured using the digital model of a lateral portion of user'sear canal; a tympanic lens mold manufactured using the digitalrepresentation of a medial portion of a user's ear canal; mating the earcanal mold and tympanic lens mold in a manner which replicates therelation between the user's ear canal and tympanic membrane; positioningthe light tip in the ear canal mold; positioning the tympanic lens inthe tympanic lens mold; exciting the emitter in the light tip; andmeasuring the electrical output from the photodetector.

Embodiments of the invention include a method of creating one or morealignment tools, the method comprising: making one or more physicalimpressions of a user's ear canal; scanning the one or more impressionsto create one or more digital models of the user's ear canal, includingthe user's tympanic membrane; digitally combining the one or moredigital models to create a combined digital model of the user's earcanal; creating a first alignment tool using a distal portion of thecombined digital model, wherein the first alignment tool replicates, atleast in part, the user's tympanic membrane and surrounding anatomy. Inembodiments of the invention, the method the method further comprisesthe steps of: creating a second alignment tool, the second alignmenttool comprising a photodetector alignment feature and a chassisalignment feature. In embodiments of the invention, the method furthercomprises the steps of: creating third alignment tool, the thirdalignment tool comprising the first and second alignment tools. Inembodiments of the invention, the method further comprises the step of:creating a third alignment tool using a proximal portion of the combineddigital model, wherein the second alignment tool replicates, at least inpart, the lateral portion of the user's ear canal anatomy.

The cable between the BTE and Ear Tip is custom formed and sized duringthe manufacturing process based on measurements provided by theclinician and the ear canal impression.

Hearing aid systems according to the present invention are customdesigned for each individual user. One of the custom elements of thehearing aid system is the cable which connects the BTE to the light tippositioned in the user's ear. Selecting the appropriate cable length isimportant for the comfort of the patient. It is also important foroptimizing the position of the sound processor behind the ear, whichaffects the sound quality experienced by the patient.

FIG. 24 is an illustration of a cable sizing tool according to thepresent invention. The cable sizing tool illustrated in FIG. 24 isadapted to assist a health care provider in accurately measuring theappropriate light tip cable length for a particular user. The cablesizing tool enables a clinician to accurately measure a custom cablelength in three dimensions. This provides a significant advantage overtraditional ear piece sizing tools which only characterize the cablelength in one dimension. The result of using a cable sizing toolaccording to the present invention is improved fit accuracy for customproducts.

In one embodiment of the invention, the cable sizing tool includes amodel BTE having the size and shape of the actual BTE to be used withthe cable. The model BTE is connected to a measuring cable whichincludes markings at predefined intervals. In use, the model BTE isplaced behind the pinna of the user's ear and is positioned in theoptimum position for fit and directional microphone location. The healthcare provider then identifies the user's tragal notch and positions themeasuring cable such that it follows the natural contour of the pinnainto the tragal notch. The BTE location is maintained while themeasuring cable is pressed flat against the skin of the tragis channeland the distance measured by noting which of the markings on themeasuring cable touch the tragus notch. While these measurements couldbe taken using a measuring cable connected to, for example a cardboardmodel of the BTE, the use of a model BTE having the height and thicknessof a standard BTE ensures a more accurate cable measurement by ensuringthat the cable measurement includes all three dimensions necessary toensure that the cable will fit the user. In this way, the cable takes ona curved 3D form and accurately indicates the overall length needed forthe custom light tip cable.

While the preferred embodiments of the devices and methods have beendescribed in reference to the environment in which they were developed,they are merely illustrative of the principles of the present inventiveconcepts. Modification or combinations of the above-describedassemblies, other embodiments, configurations, and methods for carryingout the invention, and variations of aspects of the invention that areobvious to those of skill in the art are intended to be within the scopeof the claims. In addition, where this application has listed the stepsof a method or procedure in a specific order, it may be possible, oreven expedient in certain circumstances, to change the order in whichsome steps are performed, and it is intended that the particular stepsof the method or procedure claim set forth herebelow not be construed asbeing order-specific unless such order specificity is expressly statedin the claim.

What is claimed is:
 1. A hearing aid device comprising: an antenna stackhaving a top, sides and a bottom, the antenna stack comprising: a coilantenna having a first and second side, the first side of the coilantenna forming the top of the antenna stack; a backing iron having afirst and second side, the first side of the backing iron being attachedto the second side of the coil antenna; and a spacer having a first andsecond side, the first side of the spacer being attached to the secondside of the backing coil and the second side of the spacer forming thebottom of the antenna stack; a battery stack, the battery stackcomprising: a rechargeable battery having a first and second side, thefirst side of the rechargeable battery being attached to the second sideof the spacer; a printed circuit board attached to the rechargeablebattery; a conformal coating material covering the top and sides of theantenna stack sealing the top and sides of the antenna stack frommoisture ingress; a second coating material covering the top and sidesof the battery and the printed circuit board, sealing the battery stackfrom moisture ingress.
 2. A hearing aid device according to claim 1wherein the conformal coating material comprises an organic coatingmaterial.
 3. A hearing aid device according to claim 2 wherein theconformal coating material comprises Hysol.
 4. A hearing aid deviceaccording to claim 1, wherein the second coating material comprisesParylene.
 5. A method of preventing ferrite migration in a hearing aidincluding an antenna stack and a battery stack wherein the antenna stacksits on the battery stack, the method comprising the steps of:conformally coating the top and sides of the antenna stack using aconformal coating material; and separately coating all the surfaces ofthe battery stack using a separate material.